worked for me.. are you talking about thermal epoxy mayby?
i always use isopropyl alcohol 97% for cleaning. you can try other stuff like googone or paint thinner but make sure it wont dissolve the plastic parts. if it's the heatsink you're cleaning then no worries you can even use aircraft stripper.
isopropyle alcahol i know is what ppl normally use and its recommened. but what about normal rubbing alchol? i have is that. well goo-off for my pinstrip of my car. I dont wanna use goof off on that tho. What are the odds of my rubbing alchol killing my CPU ?
i use isopropyl rubbing alcohol, i've seen a friend even use nail polish remover, his case is running fine (to my surprise).
i basically do the quick and dirty themal paste thing actually =\ errmmm, i don't do it exactly the way AS recommends, haven't had problems, yet still reaping benefits. I use microfiber (couldn't tell) to apply the alcohol, and sandwhich bags, don't bother with the knifing stuff.
Isopropyl usually works for me. For those times where I pick up a used CPU or HSF that has excessive gunk on it I borrow a nail enamel remover from my roommate [some Revlon product she keeps around here].