Bleh, I did bad.
There were some $5/$10 tables, marked "Charity casino". 4 deck, s17-- BJ pays 2-1. Wow, that's good, there must be a catch. Yup, "Dealer wins all ties". Somehow, I seemed to recall that giving the house a ~2% edge. Kinda sorta beatable. I had $60, more than enough to cover 10 "big" bets. I backcounted. 4 decks goes by fast, so there was always a table to count. One shoots up to TC +6-- sit down, win a hand, count goes up, so I switch to $10. Then things go bad. I lose a hand-- to a tie. Next hand, $10 out, split aces for 21 21, and even buy a double-down off someone (who had a 10 vs. dealer 5), and get 19. And the dealer-- gets 21 and wins. Next hand loses. I'm out. Bleh.
So I know I did wrong by betting $10. Too high a ROR (though I only wanted to win $20). But my bigger mistake was mis-estimating the rules.
Best I can find, "player loses ties 17-21" is something like a 8% house edge. If a player loses all ties-- ach, I don't even want to know. There's no feasible TC where that game is playable.
Colour me ploppy (and out $60). Lesson learned.