The bad thing about ads is they also come with a measure of lost control. As it is, we can bash liberals to our hearts content. Ads could change that. It would change a lot of things. Like what content we could post. I think it’s just too much of a hassle.
All depends on who the advertisers are. If they're in accord with the stated aims and purposes of this website, I don't see why they'd try to water down the editorial content of the site.
Now, I don't know if one can cherry pick advertisers like that, but I don't see why you couldn't. As long as you're not contracted with some ad aggregator, you should certainly have a say in who advertises on your site.