I've noticed that there's a bigger issue than harmless ads. I've been using ad-block plus relatively early. I had no idea YouTube even had ads for the longest time. Before I used ad-block plus, I don't recall any problems when making google searches.
But when I've used computers that aren't mine, I noticed every google search gives you ads at the top of the results. It's often malware too. There's no reason for the first result to be a seemingly malware infested "download manager" to download what you want when the first result on an ad-blocked browser would give you the official version of what you want, malware free. I don't know if that still happens, but frankly, I don't care to find out.