Ignoring constant normal things is fine if you already know what they say, but I'd hope you'd at least notice when things are different from normal and pause to look at it. Reacting to changing things kept our ancestors alive after all :)

Although... it does occur to me that the common person on the internet (IE: lacking adblock) may have been conditioned to avoid interacting with such things. Perhaps that's why people don't actually preview their posts? (Like its the bad part of town: keep your head down, push through, don't look or click on anything you don't have to!)