Playing Small Pocket Pairs: + or - EV?

[mxp2004]

Is playing small pocket pairs worthwhile? I don't have enough hands loaded into Pokertracker to evaluate this, and I was wondering whether anyone else does.

In my live play at B&M casinos, I have lost a bunch of big pots playing small pocket pairs when I've hit my set on the flop. I'm finding that these hands can often be counterfeited, on top of the times when you run into set-over-set.

I'd trust someone's Pokertracker stats more than my recent experience in live play, which may be nothing more than short-term variance. So if anyone has any stats on this issue -- including on what the dividing line is (e.g., don't play pairs lower than 77, etc.) -- I'd be grateful.