I would just be honest and tell them I donāt really know how to play but I want to learn. after all itās gonna be pretty hard to learn if ya donāt have guitar. Even if you have a guitar but in poor condition or not setup right, it makes it so much harder to learn. For the most part I think the people running the shop want to make a sale and have a happy customer.
Dave
When I go into a guitar shop, I always use a stuck 3-4 chord progression, combining bass picking and strumming. The pattern is a bit like Drive by Incubus. It is simple, cool, and also good to check whether the fretting hand feels comfortable with the neck.
Iāll have to look at that riff.
I always thought the go to song was, Stairway to heaven. 
Ahh yes - The Forbidden Riff 
Too inexperienced to buy a nice guitar?
SImple test:
1: Are you able to breathe?
2: Did you see a nice guitar?
3: Can you hold the guitar?
3: Have you got the money?
If the answer to the above is āYesā, it is imperative to buy a nice shiny new guitar 
What guitar you buy is down to what feels good to you and if you can afford it.
I know only too well the fear of trying out an instrument in a shop. In retrospect it can feel worse than playing a gig because you feel so exposed. The reality is that no one really cares whether you can play or not. So you donāt have to sort out a set list of stuff to play or anything ike that.
My last major aquisition was made in a shop where you were led to another room with a cup of coffee and allowed to audition the instrument in total privacy at your own leisure. That was the Gold Standard of looking after the customer.
I know the feeling. I have a desire for a Gibson Les Paul Modern in that beautiful sparkling burgundy and can afford one, but can I justify it? Iām nowhere near capable of getting out of it what it was it made for. Thatās a professionalās guitar, and even professionals sometimes use the Epiphone versions instead.
This isnāt exactly what I signed up for when I decided I wanted to learn guitar lol, getting the bug to buy more guitars. Uh oh 
Lifes too short not too? (if you can afford it)
Many worse things to spend money on.
I totally understand how you feel. I have one electric and one acoustic (Dean Zelinsky Tagliare strat-type, and Taylor 114e). I see other guitars that I like, but just canāt justify having any more with my very limited abilities. Itād be almost embarrassing to own a bunch of guitars when I canāt play any better than I do.
Yes.
Iām also thinking though maybe a really nice, beautiful Gibson might inspire me to learn and play even more? Or is that just me trying to justify the purchase? Only my brain knows and itās not talking.
When I bought my first guitar in 1997, I really didnāt know anything and I had a limited budget. I was generally happy with what I bought and I even had it set up, but I never really loved it and eventually gave it away a year later.
When I bought my next guitar in 2020 I went in to the store thinking that I knew it exactly what I was going to buy, but after trying out several guitars over a couple of hours (with my complete repertoire of A-E-D) I ended up finding a Strat that I fell in love with. Even with my limited skills, I loved how it felt in my hands and the sounds that it made. I also ended up spending about 50% more than I had originally planned, but I am very happy that I did.
I still love my guitar and any time I think wish I had something different, I can remind myself that I bought the best guitar for me. Iām generally a proponent of ābuy right, buy onceā and I think that is especially true with guitars. Iām confident that I will have my Strat for the rest of my days.
As much as I am enjoying playing, Iām pretty sure that Iāll add an acoustic to my kit. Iām not in any big hurry though because my intent will be to buy one that I have forever and I know it will take some time to find it.
So, even if youāre a beginner, I think that it can still make sense to buy a nice guitar, especially if you take the time to actually play them and find one that really works for you.
@Bon_Jon_Bovi My my ājustificationā is similar to @Rider2040.
I rate myself as an intermediate level player. I bought a used Gibson Les Paul 60s standard that has more capability than I can currently take advantage of. I tried it out at a local shop. It felt comfortable immediately: neck shape, right hand positioning, balance when playing standing (albeit LP heavy), and the tone I could produce even at my level inspires me to experiment. While I might find another guitar that has some different characteristics that I want to experience, I will not outgrow the LP. I feel fortunate that I could afford to buy such a beautiful instrument and it makes me smile each time I pick it up to play.
Iām in a Facebook group of Hungarian Gibson/Epiphone users and fans, and the number of people showing photos of their shiny new (or older) original SGs, LPs and whatever makes me think what on earth do they do with those expensive guitars? I mean, those people are completely unknown to me, I canāt recognize their name so I guess theyāre not pros. Of course, if one is willing to save for an original Gibson or Martin or whatever, more power to them, but in my mind those guitars are a sensible option only if there will be a return on investment.
My Fender acoustic is my first guitar and it cost less than 200 USD. I think it perfectly suits my needs and others like its sound too. I donāt have any inferiority complex because there werenāt more zeros in the price tag.
Well Gibsons arenāt really investments but they donāt lose much value either if taken care of.
I do like my ESP LTD MH-301. Wonāt ever get rid of it.
Lots of great advice here. If possible, have an idea of what youād like out of your purchase. And play that guitar in person for as long as you can before deciding. I play mostly fingerstyle with the pads of my fingers, as such, the projection / volume of the guitar is important to me. The first nicer guitar I bought for myself was a Taylor 4 series. It was a lovely guitar and I was in awe of it. When I played it, it was a bit quieter than Iād hoped for but I mistakenly thought it would get better the more I played it so I proceed with the purchase.
I ended up selling the guitar about a year later. It never got any louder (not sure what made me think it would). Thankfully, because I bought it 2nd hand, I didnāt lose any money on the experience.
My advice is to find someone you know that plays guitar well and ask them to go with you to pick one out. You might give them ideas too on the kind of stuff you want to play. I was lucky in this sense because my mom knew an engineer that could really jam. So he picked out my guitar for me at the guitar store based on our price range and what felt right/good to him as he played different guitars in the store. That way you know your getting a decent guitar and your not embarrassed by your own playing. Trust me I totally get that as a total beginner. I would say my guitar was around $500.00 to 600.00 when we purchased it. Good luck with choosing one!
The OP might consider asking if the shop has a practice room / private area to go and try the guitar out without the pressure of being in public.
You might also ask the shop what their return policy is, maybe they let you buy it and return if itās not the one for you?
Lots of good advice in this threadā¦+1 for the comments about getting the best guitar you can afford as it will help you be excited to play it.
I completely understand how you feel. Iāve been practicing for ~2 years, currently working on Grade 3.
About 3 months a go, I went to a music store with a friend who has been playing for over 20 years. I saw a PRS SE guitar that I liked and asked to try it out. I played a simple 12-bar Blues Shuffle in A at about 70bpm, which is the most complicated thing that I could play cleanly, not wanting to look like an idiot.
When I was finished, my friend walked over to me and said, āWell, how does it feel to no longer be the worst player at Guitar Center LOL?!ā It was the best compliment he could have given me. 