Painting - Bathroom Paint

I have been the victim of Home Depot's paint department and need help. I went there looking to paint my bathroom. The guy got me Glidden satin paint to use. I later found out that there is such a thing as "bathroom paint" and what was used in my bathroom was not it! I also found that I have a humidity problem in the bathroom due to an exhaust fan that was undersized. I have since resolved most of the humidity problem and now it is time to tackle the paint. My current paint has "wet spots" all the time. I need to know if I can paint over it with decent paint or should I get a professional to sand it down and start over?

Thanks for the help.

You can find 'Bathroom' paint here:


http://www.zinsser.com/subcat.asp?CategoryID=4

Keith