"RicodJour" wrote in message

Hey Ed. The OP did write discolored in the body, but the subject line
is "Stained wooden floor". So I guess we're both interpreting it in
different ways.

I've never seen a polyurethaned floor where the poly itself was stained
from moisture. Seems to me that the poly, once cured, is a moisture
barrier and won't absor water - otherwise, what's the point?

Considering the locations, it could be a lot of anything. Poly is a good
moisture barrier, but it can discolor from certain dyes and chemicals.