Is limping in cash game profitable.
I think it is and it is more valuable in cash games than tourneys.
Its works very well against loose passive calling stations.
And you can control the pot more.
If headsup or 3 ways.
First of all limping means that no bets occurred pre-flop, while there were players who just called 1BB to see the flop. That being said, I don't really know if you can have too many situations where there are only 2 or 3 players total limping to the flop, while it is usually a higher number of players.
Second, it shouldn't work very well against loose-passive players. They tend to see many flops and play a large variety of hands, then check/call their way to the showdown. What you actually want is to have very strong and tight range of hands against them, so that, when you see the flop and hit, being passive as they are, still get value from them.
Third, I am not even sure about controlling the pot. By limping, you give all the opponents that act after you great price to see the flop, which they should do with almost any hand. That being said, an average limp pot in a cash game will be worth round 4BB, which isn't a particularly big amount to fight over. On the other hand, make a bet pre-flop, with just one caller, you find yourself battling over 6+BB worth a pot, which then you can control on later streets by checking, betting small etc.
I would only suggest limping from the BB, maybe sometimes SB, only cause you already have the money invested and the odds mathematically in your favor.
Bottom line, don't limp.