I was wondering the opposite: How do you get as many people as possible to trigger the match so that it becomes a losing proposition to do this sort of traffic monitoring.
I don't know, I mean that is is a concern: If not enough people fake the attributes you'll get shit-listed. My answer is really that it would depend on the terms of the activity.
I've thought of a couple of ways of doing it.
One is that:
You need to be part of something, I think, that's in general use and automatically sends junk data that can't be read (i.e. encrypted nonsense) between its nodes such that being part of a network isn't distinguishable from the junk connections that the program makes on its own.
The other way I can think of is that:
you have all communications public but encrypted and posted in one (or several depending on the throughput of the service) online bins. Since many people access the same bin and download the same data but can only read their own the meaning of the message becomes dramatically more worthwhile than the traffic-a stuff.
....
The second one might actually - kinda - be being done already in some form or another now I think of it. Encrypt your message, steg it into a meme-pic, stick it on a popular forum. Since the forum is accessed by thousands of people the knowledge of who it's downloaded by doesn't get you very much :/