You should always be able to plug in at a pawn shop. They usually have a small amp behind the counter to test peoples gtr's when they bring them in to pawn.

Flea Market's? Yeah your on your own unless you have like a Pignose or Honey tone (little bitty Amps that run on Batteries and are small enough to carry).

I would never purchase a guitar I could not play plugged in. Wiring problems and etc. Unfortunately I am no Tech (change etrings and twist knobs is about it for me) so I can not offer you any suggestions on that issue.

But one thing to look out for especiallly when it comes to Gibsons. Pawn shops will usually call GC to find out what that model is selling for and sell theirs at the same price.

Good news is you can always write down the serial number on the back go online to check to make sure that A--It is an actual Gibson (not a mixed match thing) B-- what the guitar was like new/stock and the date it was made and the plant.

Ususally you can talk them down on price if it is a good guitar but old ( and you know they only pawned the thing for like no money). Or sometimes yolumay find out that after you checked the serial number they actually are selling a great stock guitar for cheap.

my 2 cents.