Re: $5/$10 Q9o on the button
 

I limp Q9o preflop after bad players whom I frequently have dominated and who will pay me off postflop with crap. When a semi-tight player open limps however, I think Q9o's equity drops because hands a semi-tight player conceivably open limps with often has Q9 dominated (QJ/QTs, K9s).

This kind of reminds me of a post Nate made where he said he was surprised at how low JTo's equity was after a few limpers since players' limping hands often have it dominated. This situation is different but the concept at play is the same, I think.