It depends on your POV, whether you are a speculator or a developer. I read JDL's question as presented as an investment. I think domain names by-and-large are undervalued, I'm not talking about the obvious junk names.
Adult domains, other than dictionary and certain longtails, are generally extremely poor long term investments. Seems like Adult WMs would rather spend countless man hours and countless dollars funneling, blind linking, trading, CJing and buying traffic than spend $xxxx/$xxxxx on a domain with natural traffic.
