Letting the tenants paint one room

[Bienes Raices]

Tenants want to paint one of the bedrooms pink (right now it's painted a very muted yellow/gray called "earth smoke"). I'm tempted to let them do it as a consolation prize in lieu of something else they asked to do but I just couldn't allow.

This might sound ridiculous, but is there any chance it won't look right when they move out eventually and it's painted back to the original color? Are there any precautions I should have them take in terms of what kind of paint, etc. to use?