I've never 'signed' an on-line petition and probably will never do so. There are several reasons.
I think that they are primarily for gathering information to sell. Their psuedo privacy policies have the usual comm major rhetorical tricks to give the impression that they have one but obfuscate the fact that it has no teeth, such as using 'do not' which can be changed at any time and not 'will not' which is an actual commitment.
I've never come across one I agree with.
I'm lazy.
And finally the most important one. They're bullshit. None of them have an option to state that one has read and rejected or is indifferent to the petition. Without this feature they mean nothing more than that a small group of highly motivated and gullible people agree with the petitioner.
Polls are better, but only marginally. As a PZ Myers has shown they are easily manipulated by the same motivated and gullible people that sign the petitions. Without proper samples they are meaningless as well.
