Watch how close your calf is to the chain..
I use orange degreaser to take the grease off of my skin. I have put it on cycling clothes (a little to pre-treat), but generally I use regular stain removal stuff on clothing.
I don't have this problem much, as my DH and son teased me mercilessly when I first started riding, about the chain tatoo being the mark of a newbie. My friend, who has been riding for 20+ years, always has a large one when she finishes a ride. I think when she got her new bike, this started, so it's something about the geometry.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport