These sorts of tools can get very annoying with their excessive warnings, but when they work, they save tons of time. We faced one bug at work where when multiple users were making a search at the same time, you would get bogus results back. With one user it would work consistently. We spent weeks tracking this downs and the problem:

== instead of .equals() in Java

The thing is, we were used to ignoring find bugs, but lo and behold it had pointed this problem out.