The ads on CycleChat generate almost enough revenue to pay for the server hosting (dedicated box with a very, very, very good support team - which means I pay far more than a lot of people do for their deds, but whenever there is a problem it gets sorted promptly and proplery!! - worth the extra dough!).
I only display them to guests though. For registered members I use Viglink (after seeing it discussed here at XF) and that is working out very well because it's unobtrusive, and doesn't add any load or slow page loading speed.
Unless you have another business or income or donations to support your site as it grows, then ads are a necessary evil. You need to generate revenue to pay for (at the very least) running costs, and I certainly wouldn't frown on any site owner who wanted to make a bit of profit for themselves too. We all put lots of hours into our sites - and the vast majority of us never get enough money back for the time invested. Love goes a long way when you're running a web site.
I have see a trend in recent years regarding news sites; 80% page coverage is ads, with the article itself taking up a thin column along the left or in the middle - the content often recycled from RSS feeds or news aggregation services. They are awful to read and don't make me want to revisit, but then I suppose some people are motivated by money more than by offering a good, fast, makes-you-want-to-come-back style service.
You certainly don't make anywhere near as much money as you once did (many moons ago, back at the start of the commercialisation of the web, I got $40 CPM from one advertiser on my web directory [which ironically is doing far better now I've removed the ads and converted to paid listing ... ]).
I rarely click on them, but accept that they help web site owners like myself earn a crust.