Whereas I think adult companies use more ingenuity and creativity to acquire traffic from other online sources, I think in mainstream there's a greater meld between traditional advertising and marketing mediums and the online medium.

Which is to say that when I've worked with mainstream companies in the past and when it comes to the mainstream companies I work with today, they're more open to and prone to pursue offline advertising (TV, radio, print) and more used to the idea of paying for online advertising even (paying for banner spots, paying for PPC SEs).

You can quite easily promote an adult site without an ounce of material being presented offline. Going through affiliate programs, TGPs, AVS portals, SEs, buying traffic, link trades, link lists.

But those options aren't really available for mainstream sites to the extent they are for adult sites - if at all.

Most of the mainstream companies I've worked with had more substantial budgets and were more open and willing to spend fair amounts of money advertising so having to be intensely resourceful in coming up with online techniques just wasn't something people put much thought in to. When you had the investment or existing capital to pump 6-7 figures in to print ads, PPC, etc it was just normal and expected to go that route. Adult sites aren't dealing with that kind of overhead or willing to even consider it.