Forget Twitter Bootstrap, if people cared what a site looks like - explain Craigslist..
You may want to rethink the ads on the home page. Text link below the banner center, remove the image boxes. You should be getting at least $3-4 per 1k imps. Maybe dropping the 'no ads when sign in'. Show ads to everybody, but very few ads. 1 per page, maybe 2, but that's it.
How much money does Craigslist actually make, though? Also not every Bootstrap site has to look Boostrappy, people just almost never bother to change the colors at all.
I agree with moving the ads though. Users who've shown enough interest to click into a page might be more amenable to target advertising.
Craigslist makes somewhere in the range of $100-150 million a year, they charge $25-75 for job ads in major markets and $10 for broker-listed apartments in NYC.
You may want to rethink the ads on the home page. Text link below the banner center, remove the image boxes. You should be getting at least $3-4 per 1k imps. Maybe dropping the 'no ads when sign in'. Show ads to everybody, but very few ads. 1 per page, maybe 2, but that's it.