Re: Under the bathroom sink leak
I say wipe everything down, then use the sink as you normally would. Waterline leaks will be evident regardless of use, it sounds more like you're having problems during/post use, which would indicate a drain/overflow problem OR it could be as simple as recaulking the sink to the countertop.
My experience with pesky little things like this is generally issues with the caulking or the overflow on the sink is either rusted or the glue (many overflow tubes are plastic now ... ) has let go.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!