This would be 2 coats of paint. 

Gross. and Gross.When folks watch the flipping TV shows they should be seeing this and not the quite antique fixtures that just need a new coat of varnish.    

If you can get more just by throwing up a coat of paint and replacing some fixtures, great. 

If it's painted...put a fresh coat on the exterior.  

I work on the Central Coat of California but would be happy to help anyone regardless of location. 

@Jordan Coates what you are feeling is perfectly normal. 

If you have a lot of water coming in,  you might need to address the problem from outside by excavating the area,  Tuckpointing,  spraying a rubberized coating and adding a protective sheathing to stop the flowing water.  

Is it a coating of water or actually filling the vent?

Most of the thicker stuff will not telegraph imperfections with the flooring below.

I prefer not having to put on a bullet proof vest and sling my MP5 under my trench coat to go deal with them.....