Chris, I'd say it's a lot easier to get good SE traffic to a mainstream blog now. There are a lot of non-recip directories mainstream directories you can submit your blog to (while adult sites are not accepted on most of them), you can successfully build a community using other community sites (e.g. Yahoo groups, Myspace and etc.), you can use viral markting tools and not be afraid that your content won't be accepted.
The only question is - what are you going to sell through a mainstream blog? As many mainstream products are a lot harder to sell than adult site subscriptions, I think that's the main thing you should think about when starting a mainstream blog.
And, I know some successful mainstream experiences with AdSense
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