$1.50 / 9m / AJs

I'm not a SnG player, but it looks OK to me.
Sets, two-pair and overpairs are strong possibilities.

but betting so small he only needs to bluff once in 5 times for this to be break-even

Any real experts want to check the turn?
If so, what would you call if MP bets?

Now that I look at the hand again, I really don't know what he is betting with OTR that I beat.

Considering that he is a REG, I dont think that he is betting there with JQ or JK as he is checking that behind.

If he is bluffing, I think that he would have chosen a bigger size.

Normally I would check to the aggressor on the flop, but leading multi way isn't to be a bad on a pretty wet board with top pair top kicker.

Cbetting turn for protection and thin value seems alright. If you would check you need to call at least once.

River is tricky indeed. Tough to expect a reg would float 2 times with the intention to bluff the river. It's that you get nice odds. Otherwise I would fold for sure.

Cheers,
SDK1987

@SDK1987 - Do you check-call on the flop or check-raise? If you check-call, do you continue check-calling all 3 streets if he is betting 1/2 or less?

Most likely check/call. It will be tough to get better to fold or get get value with a raise. Only a flush draw will continue what you beat on the flop.

If villain would barrel again on turn and river I would consider to fold the river, but it depends on reads you have on the villain.

Versus late position opener I would aim to x-r flop if hand was called pre. Now versus middle position and pot being 3way it might be bit questionable. Though I would not mind it in micro stake games in general as I would expect people to overplay hands. But you said villain is reg so maybe that is less likely.

In general I would have no donk bet range on this flop. Turn is not great spot but we can get value from weaker Jx and some pockets with flush draw. On other hand there are numerous hands we might be behind depending how villain play flop. So I would not mind turn check.

But then we come to problem part as we are out of position. Villain gets to decide what to do on river if we check. We are now in this spot with ultimately fairly mediocre holding we would love to just check to showdown. This situation already started to develop from flop donk and turn barrel.

Villain can have overpairs and some flushes as our main concern. Is he bad enough to value bet weaker Jx is important question? What bluffs he could have? Most likely ones maybe some AK, AQ, KQ with one spade.

Ultimately donk betting flop is kind of issue as it creates situation where villains range to invest chips into pot will tighten. If hand was checked to MP he might make cbet light. Same of its checked to CO. But if facing bet they likely respond tighter.

Also one thing to ask is what is our respond if we get raised after donk betting? Are we willing to stack off? In general when donk betting we want to have hand we have kind of clear answer to that. This spot versus potentially reasonable opponent I would not be thrilled to face raise.