On guitar store etiquette
Hey, show some respect and you'll earn it. (At least at the smaller stores where the staff can get to know you. All bets are off at the chains where staff turnover is high.)
It's no big deal to treat the gear as if it isn't yours, because... hey, it isn't yours! Make sure you're not wearing a belt with a big buckle (or at least cover it with your shirt), take your rings off, ... treat the guitar as if the store's policy is "you scratch it, you buy it." The staff will appreciate your concern, as will the person who eventually ends up buying the guitar.
I even think there's a place for the kid with a paper route who wants to try out an expensive guitar. Don't be arrogant. You have no 'right' to play an expensive guitar. But be up front with the sales guy, tell him how interested you are in the guitar and how long it will take you to save the money... just be honest. A decent sales person will respect your honesty and help you out - without giving you free reign of the store - and will be a good resource for you when you do eventually save the money you need for your dream guitar.
Not all salespersons are jerks. They get a lot of attitude from know-it-all customers, and some of them have a defense mechanism to put down someone who fits their 'profile' of a difficult customer. Prove 'em wrong and you'll make an ally.
Again, this is all about building relationships. Spend your time somewhere where the staff is likely to be working at the same place a year from now.