Anyone know how to make a plain white room an asylum? I'm wanting to make it look like it hasn't been taken care of. Do light gels work well?

Light gels change the color of the light... they don't do anything to the look of the set.

To make it look old and uncared for you might try putting peeling paper on the walls. Try to create areas where it looks like the wallpaper has lifted and peeled. Water stains. Can you paint the wall with greys and browns and add spatters? Paint cracks on?

Well, it's actually in a dorm room, and we cleared it out and put a crappy, rusty, bed in there. But I don't think we can paint the walls. Could just putting dirt on the walls give it that effect? So gels wouldn't make any mood to the scene?

Dirt would probably help a lot!!

Gels would definitely change the mood of the scene, but there are no hard and fast rules for any of this. Do you want colored light? Then add gels! A greenish color might feel creepy. If you can get it to be soft, by bouncing off of a wall, or shining through diffusion, it might help too.

I'm sorry I can't give you more specific answers than that, but you're really the only one who knows what you're after, what you have available to you, what your creative vision is. and what it looks like in that room. Best of luck.