Checking in the dark

[TakeMeToTheRiver]

So you are in the SB at a 1/2 NL table with a trash or marginal hand. There are several limpers and you know the BB is passive and is unlikely to raise without a real monster. So you throw in another $1 and -- after BB checks -- you pat the table and say "check in the dark."

I do this on occassion. Being in the worst position, I figure I am only going to stay in this hand if the flop hits me very hard. If I check in the dark, there is no way to get a read on me -- indeed, I can avoid looking at the flop and watch my opponents when the flop comes. I have won some significant pots with this move when I flop top two pair on a ragged board or a straight with my offsuit two-gapper.

What is the downside of checking in the dark? Am I missing something? When do you check in the dark?