If their clothes are stained, have holes, dirty, etc., we won't rent to them. 

One thing I totally recommend is getting mattress protectors you can put under the sheets to protect from any liquids or stains, this will be a lifesaver as you only need to replace the protector and not the whole mattress.Hope this helps, let me know if you have any more questions!

I wouldn't spend a bunch because they will get stains and worn no matter what you decide to buy.  

Microfiber is great for kids beds as they just don't hold stains like cotton.The Berkeley comforters are synthetic and they work great and we have had zero complaints.

@Mike Franco also consider acid stained concrete for durability

Just in my personal residence I've found that grey hides and obscures dirt and stains a little bit better.

I'd just like to add that some of these old homes have outstanding woodwork, stained glass, fireplace mantels, etc.

I have always rented to very reasonable people who I suspect would note the difference between a house that requires normal cleaning following a turnover and one that has urine stained carpets, chewed up woodwork, etc.

Carpet in large upstairs bedroom stained and had to be replaced 600.00.

I will spare the story behind these places but my most memorable things included:Someone sleeping naked on a sofa in the middle of the living room (in the middle of the day).A house that had used (that is stained and dirty) underwear hanging from the dining room chandelier and used "feminine" products just thrown on the bathroom floor.PS I love the pics...