Can't lump all re-sellers of games into the same bucket.
Many of the comments above have described the negative connotation of what many of us consider 'flippers'.... in which case, I'd say they resemble 'scammers'. I've found the most irritating and immoral flippers live on Facebook, Craigslist, and OfferUp.
I've been burned by a scummy flipper (@jamesbon1) so now I ONLY buy from other 'collectors' or 'resellers' because they generally represent their games properly and care about their reputation.