Am I unusual in not noticing ads online?

This article about Twitter’s going public says:

Like Facebook, Twitter makes its money primarily by selling ads, which gain a lot of their value from the advertiser’s ability to target specific groups of users.

I’m so used to ads on social media that I don’t even notice them anymore. I must somehow register their presence, but I seem to automatically ignore them. This is true of Facebook and Twitter - I’ve looked at both this morning (I found the article I quoted l...