Amazing Quadruple Check-Raise in 30-60 (long)

[Ulysses]

So, what about the following pattern. It seems like I see it very regularly. Is it cheating?

Two guys who know each other sit next to each other. Non-regular player sits down and raises pre-flop. Both guys call. Flop is rags. Checked to the raiser, who bets, call, call. Turn could be another rag or a scary card, that say puts a straight on the board. Checked to the raiser, who bets. Guy #1 raises. Guy #2 3-bets. Raiser folds. River comes, check, check. Guy #1 shows bottom pair. Guy #2 mucks. Or something like that.

I see this happening all the time. It never bothers me when both players are guys who are just super-aggressive all the time. But I get a bad feeling when it's two guys who only turn aggressive when they sit next to each other.

The other thing that typically happens with these tandems is they'll open-raise and 3-bet, then go limp after it gets heads up. That doesn't affect me much, since most hands I'd play are 4-betting hands in that scenario. However, it can't be great for the game when non-regulars see the QTo take it down after 3-betting.

Any thoughts on this kind of play?