Why were you there?
I go to about 6-8 shows per year (two different circuits) and always enjoy and get amused by the experience. IMO, there are three types of attendees..
1. Newbies getting into vinyl buying just about every cheap copy of classic rock albums they can find. Most use Crosleys and its a hipster thing.
2. Collectors who could care less about sound quality and who most likely will never listen to it. But its rare and collectable. And these same types will demo records they are interested in on the vendors Fisher Price or Kenner Close and Play that the vendor happened to bring before they lay down hundreds of dollars. BTW, ever see the preponderance of junk TT’s at these shows demoing records?
3. Then there is me. The audiophile listener who is looking for the best sounding, most pristine copy of a title I really enjoy. I once made a deal for $25 on a mint Japanese 12" 45 rpm pressing of a title I really like. After the deal was done the vendor then offered to play it on his Fisher Price. I told him if he does that, he is not getting my $25.00. He bagged it and I went home with my one purchase. It is now one of my two best sounding reference recordings.
Since you mentioned a lot of junk, I suspect you may be number three. If so, get to know the vendors that routinely do these shows. They will bring and hide the good stuff they find for you - Japanese pressings, sealed albums, 1/2 Speed Masters, etc. If you just buy one at a show and its a keeper, then its a success.