So long as it is practical. Evil only works for me so long as it makes sense. Kill someone for fun? Nope. Kill someone because they have an artefact I want?
Yes, I can do evil, if there is some purpose or justification behind it. I was never able to do Bioware evil, as I found it too unenjoyable - being a cruel and murderous person for... lols? Why would I consider being evil, and if being nice leads to more satisfying places without losing anything?