Raw colors - straight from the tube - make me cringe. I've just got to "dirty 'em up" in order to get inspired.
This particular painting (Day Lilly Still Life) is a good illustration of the use of "palette dirt." I scumbled into the halftones in the "white" cloth to give it an "unusual" but more lively color.
At the end of the day, the colors remaining on my palette and scraped into a pile are often too good to toss out.
There is always harmony in using "palette dirt" (usually in halftone and shadow) - after all it is from the same colors used in the larger painting. You can always adjust the "dirt" to be warm or cool as needed.
My landscapes improve with the liberal use of palette dirt. This painting, Meander, is small (8x10) and was painted at the end of the day with lots of piles of "dirt" left over from another painting.
However, you must be aware of the "color temperature" of your "dirt" and use it wisely, i.e., halftones are cool - shadows are warm and deep shadows are "hot."
You cannot mix these up even though it isn't always obvious. Color is relative to what surrounds it. There can be warm and cool blues for example and you need to know which is which or it won't work.
Except for the skin tones, most of this portrait of my father, Carl Christensen, is "palette dirt." I even scumbled warm "dirt" over "cool" dirt to make the background.
Using Palette Dirt offers me a wonderful range of neutral colors that I couldn't possible invent on my own.
If the pile of "palette dirt" is big enough, I save it.