I was at an auction that had 25 longs (they were all moderns, bagged but not boarded in a long) where they did buyer's choice and the guy with the winning bid took all of them but 2-3. I was floored because I had time to make notes on which boxes I would buy based on price, it was strictly a volume deal and there was not much of value other than some minor keys, more popular titles, etc. Anyway, the buyer was clearly not a knowledgeable comic seller because he had $1 bins buys at some point down the road. After the dealers cherry-picked those books I don't know what he did with the bulk.
And yes, I couldn't agree with you more regarding comic buyers at estate auctions. The last 10 years or so, every comic auction I've been to has seen a ton of drek and unsellable books go for more than they would anywhere else. I'm convinced buyers at auctions, see these comics and think, 'well I can get at least a buck for this', and lap up the crud!