You're asking about the efficacy of passive messaging - I don't think it would work if you asked people. Likewise, I think simply doing it is more likely to annoy people than incite passion.
Visibility is the issue, not understanding the problem. I think the message of "the internet could be slower without net neutrality" is the one that needs to be delivered. People generally know what "slower" means.
As I mentioned, a standardized message would probably be more effective, but it's also not something that would be particularly exciting to share on, say, Hacker News.
I daresay annoying people is the whole point. Combine that with the logo example given upthread, and you've got a very effective campaign going on. What I see happening:
"Why do I keep getting this bloody message with Comcast's logo on it every time I hit random websites? readreadread Fucking Comcast at it again.."
Visibility is the issue, not understanding the problem. I think the message of "the internet could be slower without net neutrality" is the one that needs to be delivered. People generally know what "slower" means.
As I mentioned, a standardized message would probably be more effective, but it's also not something that would be particularly exciting to share on, say, Hacker News.