If you buy on a very reputable site like Audigone, much of that inherently gets filtered out. I don't see a lot of what you're describing in your post, other than the sometimes questionable pics/stock photos. I'm not sure what's wrong with "gimmicky" pricing, as we 2nd hand sellers take our queues from retailers. We wouldn't say $995 at BB is gimmicky. Also, you'll pass on a lot good deals if you read too much into firm pricing. If it's more than you want to pay, move on. I've bought things at firm prices and snagged really good deals to the extent that had I waited another x minutes, it would have been gone.
If I'm interested in a product, I'll ask the seller a question to gauge responsiveness, tone, etc. I was interested in a Parasound amp one time and did just this. The seller took days to answer my questions and tried to answer in one word or less. I didn't care about the seller ratings at that point- I moved on. By and large, I too base most of my decision on the seller ratings, as they speak volumes. But pay careful attention to the reviews. Sometimes they're through no fault of the seller and the buyer wasn't reasonable, if they're limited in number.