Buyer beware. When it comes to garage/yard sales, it's an "as is, no returns accepted" policy for the most part. I've never returned anything and i've been burned more than once. Intentional? Maybe, maybe not but in the long run it was my fault for buying the item to begin with. If it plugs in test it before you buy. Granted, something that runs on a rechargeable battery is not really testable to the point you can tell if the battery is good. To that, treat it as if the battery is bad and needs replaced. Most of the time they are bad anyway. If it's supposed to be silver then you better know your silver. Never take someone's word for it. Someone may be trying to get over on you and someone may not actually know that it isn't silver. I had to explain to a woman last weekend about her silver puffy heart locket that she though was sterling. It was clearly marked Alpaca... not silver, sorry lady. Looks a lot like silver but it isn't. Pottery and glassware, thoroughly examine items for chips, cracks, repairs etc. in bright light if possible.
And yeah, if it's a flea market vendor that is a regular then depending on what it was I may consider a return on something.