http://pornblogspace.com/
It's set up better than any other free host I have ever seen and it's made for adult.
Kaktusan is someone who is known in the industry. If you're an adult blogger you probably already use tools he made like link organizer or blog organizer.
I'm not saying you shouldn't host your own stuff, I'm just saying if you use sites like tumblr you should try this host.
There are also 4 other domains he owns so you can get any sub-domain name you want. Right now it's still in the early growth stage so you have time to build up a lot of traffic.