From Hero's point of view, there are 21 non-brick cards out of the 46 unknown cards
- 9 non-heart jacks, tens and sixes either make a bigger straight with a single card or counterfeit Hero's straight.
- 12 cards pair the board.
From villain's point of view (but knowing Hero holds two hearts) there are seven non-pairing hearts that also could prove to be scare cards for someone holding a set or two pair or top pair+..
Hero needs to be careful about selling cheap cards, much less giving free cards. A cheap card from Hero means he is pot committed under most situations. (Maybe he could use his table read vis-à-vis the old man coffee) That makes it harder for villain to make a mistake with modest draws since he gets both the direct odds from the turn call plus the implied odds. Also any mistake made is significantly smaller.
If we knew villain's holdings were limited to worse flush draws, one-pair hands and perhaps two pair then maybe Hero could safely make a fancy-play small suck bet knowing the risk was minimal. The problem is all of those 21 scary river cards complete several of the "safe looking, four out draws" Hero isn't going to be able to dodge getting stacked on hands he loses on the river.
Almost as important, hero gives up value vs hands like
that would have called an all-in on the turn, but will snap fold to a river brick unless they make their hand. Or, Hero checks on a river ten (for example) and fails to even attempt to extract value from sets / two pair. Or sets that couldn't fold to a turn bet but give up calling their last chips off looking at a 4-straight / 3-flush board.
Hero also needs to be mindful about setting up bet sizing tells if these are people he sees a couple of times a month. Doing plays like this as regular course of business eventually will teach your villains when to be bold and when to duck away from trouble.
I think Hero is best served by keeping matters simple. It is always tempting to second guess a decision not to slow play / soft play after we see the table fold. That doesn't mean the original decision was wrong, just that we are disappointed by the outcome.
DrStrange