When starting out in the mixing world, I would say the misuse of compressors is second only to the misuse of EQ. When gain matched, a before and after quick listen to a moderate to heavily compressed tracks (especially drums) can sound very flattering in the first instance and is often left in place without any after thought at final mixdown.
While benefits can be gained from compression as an effect there can also be a downside.
The famous engineer Bruce Swedien' once
I've recently had a few enquiries about basic room treatment as I'd noticed some clients had rather coloured vocal sound that was the result of early reflections from an untreated recording space.
Most artists today favour condensor microphones because of their flattering detail and sensitivity. The downside of these mics is that they also can pick up the sound bouncing around the space you are recording in which can sometimes effect the colour and quality of the signal in