Depends what you're considering to be a marginal hand. I would never call with something like Q7, K6, etc., because those hands are so easily dominated. For instance, lets say you limp in with K6, and the flop is something like K92. In this scenario, you've hit top pair, and short of a huge overbet, you'll call almost anything; however, there is still a decent chance that you don't have the best hand and you easily could be dominated.
That being said, I'm fine with playing suited connectors (and I mean hands like 89 suited, not 34 suited) and suited one gappers (again, hands like 79 suited, not 35 suited). These are good drawing hands and a lot of the time, it will be relatively cheap to stay in hands and your implied odds
are very good.