[PandG]

Thanks, Phanatic Luvr! That's not the case as all our sinks' P-traps are always wet.

Last year we had occasional bouts with smells from the sinks. These are the master bathroom sinks, so it wasn't the traps drying out. It was--according to our plumber--algae growing in the sink overflow drains. We use a funnel to pour some vinegar into the overflows and the smell goes away. Stays away for a while, too!

Last night's incident seems to be something else.