It all depends on your goals for the bike. There are a very, very few high-end bikes that, if found with absolutely horrendous paint, would be financially worth the effort and expense to refinish. The vast majority of them aren't. However if you're looking for the satisfaction of taking something tired, abused and neglected, and you want to make it look AND ride like new again, go for it. I personally love doing that. I don't do it because I expect to get my money back if reselling. I do it because I love taking something that's been discarded as worthless and making it beautiful again.
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"My only true wisdom is in knowing I have none" -Socrates