is this smart/profitable in the micros or generally a more advanced play?

A. Not very profitable probably at 2nl, 5nl, and probably not 10nl.
B. Applies more to heads up play, which most sites except AP/UB don't offer. Even then I don't think it's very profitable at 2nl/5nl unless you're playing a regular that knows what he's doing. Even then if he truly knows what he's doing he might call just because he thinks you're bluffing.

i think it means heads up in the pot, not literally heads up? and i play 10NL rush.

Generally speaking I think it will still be profitable in the micros, just don't get carried away with it. Even the worst players are able to recognize that "any heart wins" on the board and if they don't have one they can't call.

I don't think it will be as profitable as it will be at the low-stakes because you're going to get more micros players that will be comfortable calling you with an extremely low flush (eg. holding a 6 or lower that makes the flush). I still think you'll get plenty of folds betting it though, and it will be more profitable against the regs (of which there are many at the micros).

at micros people will tend to see 4 on the board, that they don't have one, then come to the conclusion that you must have it. higher up, people get better at hand reading and understand polarized ranges more. at micros its almost always +ev to bet when u have no showdown equity in those spots. u won't fold out any flush or even 2 pair or better, but considering u don't need to bet much more than half pot and u can get air and 1 pair hands to fold most of the time, it's +ev

Yes, I think it's a great bluffing spot and you will get a lot of folds. Even people with relatively high flush cards (J, T, 9, even maybe a Q) will have a tough time deciding whether to call, as they will very often put you on the nut flush

I myself have folded strong hands (even a straight) when villain strongly bet a 4-flush on the river and I didn't have a flush card in my hand. Micros players may suck at hand reading and board reading, but one type of hand (and type of board) they all can read very well is the 3-flush and 4-flush , so when someone bets a 4-flush on the river, both players clearly understand what the bettor represents. So, as a general rule, people in the micros can only do this move with the made flush, and without a read that the villain is capable of bluffing in such a spot, it is a bad call. Now think how many of your opponents have a read on you that you can be bluffing there? Very few, and therefore very few will call

Best theory for the micros is?

beluga

Here's why bluffing flushes at micros is not profitable


Poker Stars $2.00+$0.09 No Limit Hold'em Tournament - t15/t30 Blinds - 2 players
The Official 2+2 Hand Converter By DeucesCracked Poker Videos

Hero (BB): t1565 52.17 BBs
BTN/SB: t1435 47.83 BBs

Pre Flop: (t45) Hero is BB with 5 2
BTN/SB raises to t60, Hero calls t30

Flop: (t120) A 7 K (2 players)
Hero bets t80, BTN/SB calls t80

Turn: (t280) 8 (2 players)
Hero checks, BTN/SB bets t180, Hero calls t180

River: (t640) 8 (2 players)
Hero checks, BTN/SB bets t420, Hero calls t420

Final Pot: t1480
Hero shows 5 2 (a flush, Ace high)
BTN/SB shows K 3 (two pair, Kings and Eights)
Hero wins t1480

I think this theorem should only apply against good players, if the board was 3flush then it'd be better to bluff against fish imo

Doubtful, if said fish has ANY spade he's probably redrawing to hit now. Plus just being stations in general mean they'll call with 2nd pair on a 3 flush board that doesnt hit anyway.

I think check/calling with the King High flush in the theorem is wrong at the micros.