Sheen looked like a bag of crap in season 8
The writing was on the wall for sure. In the early years, they'd do his makeup to make him look either sick or haggard whenever he was on a three day bender of booze, broads, or both. Otherwise he looked healthy.
I was watching last night and it's clear that by season 8, even the makeup department couldn't make him look not like a homeless meth head they dragged in off the street.