Red is the most difficult color to pick and paint with (in my opinion). I have 3 red rooms - one is a Benjamin Moore deep, deep brownish red (from their Historical collection - can't remember the name right now), one is a deep true red, and one is a paprika red (actually has some plum in it). BM store told me just to paint 2 coats & I'd be fine. No primer needed. Wrong! It took FOUR coats & still has some streaks to it under certain lighting. With my 2nd red color I used a red tinted primer, still took 3 coats of the red on top to get an even color. Then Sherwin Williams insisted I had to use a grey primer 1st - made me nervous but I did it -only needed 2 coats of red on top of the primer. When I had a professional painter come & do my 2-story ceilings he confirmed that red needs a grey primer, not a red tinted priner. So for whatever my walls were painted with prior (typical contractor graqde paint), the grey primer was definitely the way to go!