I do a lot of special effects work and tend to use "dirt" effects regularly. Having tried the different ones out there (alcohol palettes, cream palettes, powders and sprays) I really wanted to try the Ben Nye Clean Dirt and Clean Grease.
Both come in a small container (the small size is good for a single application -- I'd recommend the 8 oz. if you want to do more than that).
The product appears to be heavily oil-based. It's a very oily "mud" like consistency. The Clean Dirt is a very brown color (sort of like a light mud) while the Clean Grease is a black color. Dirt is used to recreate a mud look, grease to recreate a mechanic/oil type of effect.
The product applies very easily with fingers -- it stays oily/wet throughout and does not dry. I thought the effect was good, but it does require you to spread it around quite a bit to prevent the look of a single spot of mud/grease.
The thing to know about this is that A LITTLE GOES A LONG WAY. I made the mistake of using too much at first.. I've since used it much more and just a bit continues to spread everywhere.
That's where the word of warning comes in.. this stuff spreads onto anything it touches and will permanently stain most of it. Costumes, shoes, shower curtains, you name it..
Be very careful if using it on location -- it's very difficult to remove (as you try to remove it, it simply spreads around). I lost a few outfits to this (which is fine) but if it gets into your car or other places…