Porn stars. Now you're interested. Here's the thing: people regularly acknowledge the blonde vixens of adult entertainment (Waffles is following up with a Hottest Blondes Top 40 list a little later today), but the brunettes sometimes get kicked to the curb. Maybe it's difficult to categorize some of them because they change hair color as quickly as they do (se)men (ah, see what I did just there?). In my research of the hottest brunette porn stars, I spent considerable time laughing at porn…