The overflow drain in my bathroom sink really smells. I took it apart and it's moldy. Is this ok?

Question

Or should I get a new sink?

Answer 1

Mine was too some years ago.  Practically clogged up with it.  I cleaned it out, then cleaned it out again with a bleach solution.  No problems since.

Answer 2

clean it out and pour bleach straight into the overflow in the sink, then some down the drain. let it sit in the trap for a while, then rinse.