Have them leave at least 1 bundle of shingles so you have some for repairs and also will have the shingle manufacturer / color. 

If it's a stone tile, their colors are based on the slabs they came from. 

Postcardmania.com they're designing and mailing 5400 colored postcards for $2k total.

Sometimes buyers can have mental block about stupid things like paint color.

I don't want them changing their mind every day about the color of the backsplash in the kitchen. 

The problem with getting your information from an online discussion forum is that many if not most of the sources have opinions but little actual knowledge and very few any personal experience or success.Adverse possession, either by color of title or claim of right is public policy in every state and commonwealth in the U.S. 

All the same color?

Does anyone have a favorite color gray to suggest?

There is no coloration between rent payment and repairs.

And besides, I would prefer an investor who pulls out of a deal because it didn't pencil than for some "princess" to dislike a property because the lighting fixtures weren't her color, or the home wasn't feng shui.