Seems like whoever told you that checking top pair when villans could be on a draw has the concept backwards - when the board is dry and the turn does nothing to change the texture of the board, then we can check to induce bluffs or get worse
hands to valuebet rivers for us -- but if the board is wet we certainly want to charge our villans for their draws - both for value and protection. If you give draws a free card they get to realize their
equity without investing anything more into the pot.
I think alot of times people fear the reaper and say "well these idiots never fold a flush draw anyway, so no sense in me betting because if they hit it I'm just going to lose more" - and the reality is this attitude is not only ignorant, it's completely counter productive to playing the game as a whole. Opponents will miss their flush draw roughly 65% of the time, so that means I will win 2/3 of the pots that I continue value betting in, which also means I will win more chips by doing so. Who cares if they draw out on you, its only one hand. Don't get hung up too much on why they called you, a big reason is improperly sized turn bets - did you give them a good price to call? Maybe you shouldn't...don't price them out by being a fool and betting ridiculous, but bet larger to charge draws for hanging around the maximum with your strongest holdings.
Basically in a nutshell, we want to charge villans who have draws the maximum within reason, so we give them a bad price, they still call with their draws, and we just win more chips long term. Once more to drive it home...When draws can and will call you - bet for value and protection - charge the draws to continue - make more money!
Hopefully this helps. Seemed like you had your head wrapped around the subject pretty well. There are of course some nuances post flop that will stop us from betting and such - but in general, you get the concept here.