Some people like blue ink although if one studies colors and how a color motivates its easy to see why red is the choice.

It's just the best ink color.

I've had one tenant on a month-to-month for 15 years now.Invariably I will have new tenants ask for minor updates (so far just color of paint) and I couch that with saying that I generally don't entertain those requests until they've been there for a year.  

It doesn't cost me a lot more to do a neutral color and paint trims white and make the house stand out.

@Joel Owens cinder block walls and industrial lino works have seen it many times. for me only provide a stove... period. but I do like the prison concept.. seems like we are the wardens.cage the condenser..When I was buying and rehabbing I always put in a new sewer line to the street if it was 20 or more years old could get it done for 1 to 12oo before its an emergency and its one of the biggest maintenance items.And then the obvious I never put carpet in C properties.. most have hard would floors Paint them dark colors. let them use throw rugs. etc etc.bottom line is these homes are lived in roughly

I have found that standardizing paint color and not allowing any smoking really speeds up turnover unless it's a total remodel.  

However there a large amount of variable besides prospect demographics and geographical area. 1- days between hits2-message3- mail piece type4 - color of envelope if letter5 - ink6 - use of pictorial messages 6b- which picture works best7 - order of messagesAll important factors.

While they kinda thought they got all of them, the next door tenant had already moved after complaining to the health department about the rat problem... for a bit of additional color, the PM was complaining that the lady who called the health department was the problem.

Sometimes it can be as simple as changing the color of paper, or the type of envelope.

Are you sending b&w or full color?