I painted bathroom tiles with eggshell paint in my bathroom and it looked really good - only be careful as they don't clean off as well as tiles - I dyed my hair three days after painting and my then-husband had to repaint them al!
Also, did kitchen tiles with Ronseal one coat tile paint (no primer needed). What a disaster. Does what it says on the tin - my a*se. after 2 coats I had to scrap it all off and it took a total of 8 coats to cover the medium coloured tiles. looked better as long as you didn't look too closely.