'Dja ever notice that deep paint colors don't seem to cover as well as lighter colors? There's a simple reason for this and it involves a recent post about titanium dioxide.
Let's say you've chosen a deep orange for your living room - this really happened about three weeks ago (along with deep burgundy, chocolate brown, etc). Because these colors requires so much tint to achieve the deep colors paint manufacturers must remove some other ingredients to make room.
One of the things that's got to go is titanium dioxide - the chief component that gives paint its hiding power. That means you'll almost certainly see the original color through the first coat, probably the second, etc. I've heard of professional painters applying five coats (in addition to the old trick of using a gray primer coat) before they achieved deep and even coverage. Paint quality really comes into play here - low quality (and low priced) paint never covers very well; you'll eat up any savings with increase labor costs. Or simple aggravation if you're a DIY'er.
Paint quality certainly affects coverage, but at a certain point you simply bump into the tug-of-war between tint (deep colors) and hiding power (titanium dioxide or similar). As there's only so much room in the can; something's got to give.
This is why we always make a point to ask about colors when we first meet with a customer to discuss an estimate. Most people assume that paint is paint and colors are colors and they appreciate an open discussion about how their color choices can affect the cost of their project.
And not all paints are available in all colors. Manufacturers make different paint "bases" - some are formulated for lighter colors and others are for darker colors. So, for example, if a certain high quality interior wall paint isn't available in an ultra-deep base so we'll have to use a more commercial-grade paint for that particular color. Just some of the trade-offs that manufacturers make between product line, cost, sales volume, etc.