How do I know when to use the charge density or not in a Gauss problem?

[Parad0x88]

I feel that I'm always struggling with these kinds of problems since I never know if the information is to be considered a density or not. Is there any trick/key words I should be on the look-out to determine whether they gave me a density charge or a point charge?

 

[mfb]

Look at the units.
Coulomb -> point charge
Coulomb per volume (or area, or length) -> charge density per volume (or area, or length)