Some are very particular about finishes/colors/materials, some aren't.

Stick to 2700 K or 3000 K color temperature and you should be fine.It's been my experience that return on investment in water efficiency typically exceeds initial ROI on a good piece of real estate. 

When I came later to inspect, I found that the area that was damaged had a different color and type of vinyl and it ruined the value of the property.I give these anecdotes because you may be going down the same road. 

If they feel like their is mold although someone has already inspected for that ... you can get one of those water scanner things (sorry I have no clue what it is called) but it essentially checks for moisture (it shows certain color based on the moisture) also I would remove the base boards and cut about a foot of the dry wall to see if that is wet.

Vinyl we definitely be less maintenance intensive and if you pick a color that won’t look ugly when it fades it will probably be cheaper.

- Water-color or pencil color?

I would not recommend this strategy only if you absolutely need total control of a project, you really want to pick out the paint color, and think you will be a better operator than someone who has been doing this professionally for years/decades.

-If you mean they suck as an investment overall, disagree =)This is all my personal experience but most people can relate to.1) For example, If your goal is 4 residential homes, than a single 4 plex will get you there faster2) 1 roof instead of 43) Fixtures, appliances, colors and materials from the same vendor4) Property tax bill from the same county vs 4, making automation easier5) A single property management company vs 4, making automation easier6) Same HOA company (if any) making automation easier7) You'll take less time doing your taxes and your CPA won't charge as much.8) Even my condos are WAY better and easier to manage than my single family home.

My recommendation is go with a color on the floor, as the white gets gross quick. 

Whether someone is legal or illegal as a barometer for being a good tenant is probably about as useful as using the color of their shirt as a barometer.