1. [late 18C+] pleasant, admirable, well-dressed.
2. [late 19C+] sexually alluring, attractive; also used adverbially (see cit. 1989).
3. [1910s+] of a person, smart, sharp; often as tasty geezer; or prob. criminal; thus tasty villain, a known criminal.
4. [1940s+] of a thing (usu. some form of criminal plan), valuable, worthwhile.
5. extreme, excessive.