I don't think of sex as "dirty." Even the kinky stuff. If it's consensual, it's cool with us.
softcore porn. The women are airbrushed (CGI or whatever) and have had massive plastic surgical procedures and usually naked... the men rarely even take off their pants, and aren't even all that good looking. You NEVER see any dick. Never any actual penetration, not to mention other fun stuff. NOT my kind of titillation. I prefer hardcore porn, and.... most usually hardcore sex.
My thoughts? Depends. Sometimes they are just about him holding me or cuddling me... sometimes it's much more detailed and hardcore than that.
I probably think about sex.... every 2-15 minutes when I'm not wrapped up in work. (I work with infants, and I'm constantly busy while I'm working so sex never crosses my mind when I'm working.)
Stress tends to cause My Man and I to have more sex to relieve the tension. It works well for us.
But, I don't consider any kind of consensual sex "dirty" so I can't really relate to the question that well.