Diablo made some very good points in his post.
A pocket pair is far less attractive in a ring game than an MTT or SnG. The lower the limit, the less attractive they become.
In a ring game, I will normally consider calling a raise with 1 overcard, depending on the preflop play. When a raiser gets raised with overcars, you are most probably beat and should seriously consider folding
PP's in MTT's however are a far different proposion. A raise preflopopwill normally push out a fair few players, and players holding cards like A-rag of KQos are far more likely to lay down to a preflop raise in an MTT than they are in a ring game.
The problem with medium or low PP, especially when you are out of position, is that its very difficult not to push out a bet, even with overcards on the flop, as you dont want to show a weakness or give the opposing player(s) the opportunity to raise into you
For example, I was at the final table of a 15K MTT a week or so ago, I was chip leader and dealt 4 PP's in the 1st 10 hands. I got atleast 1 caller to every raise I made and lost a fair chunk of my stack betting into a flop with overcards, knowing a raise to my bet meant I was possibly beat and may have to lay down my hand.
Low pocket pairs are nice cards to have but I feel you either have to limp in or make a nice raise, any callers with overcards and you either have to
bluff them out or lay down your hand