Dragon Ball - Vegeta and Trunks

Does the gravity chamber also double as a tanning booth?

I can answer that one, in some shots while Vegeta was wearing a pink shirt he would occasionaly have really dark skin for some reason. So the artist was probably basing his design from one of those shots. Here's a side by side comparison of him looking normal in one shot, and then having dark skin in the other one.

This happens quite alot in the android saga with just about every character, though it's nowehere near as noticeable as it was in these few episodes