Honestly in other cases they are. I had personal experience developing tools used for Howard Dean's 2004 primary campaign (as a volunteer not staff) and in that case it was certainly real.

I'd be very, very surprised if the ones used by Ron Paul and Obama weren't real. They have good engineering talent there, and (in the case of Obama at least) good political talent. This runs contrary to both.

I was going to check and get back to you, but I can't find one on either of their sites.

They run them during specific fund-raising drives.

You can also see them on peoples personal MyBO pages.

Can confirm that the thermometers on Obama fundraising pages (MyBo and others) are real (not simulated and not manipulable). It's a feature of the donation software they use.

(My employer develops it.)

It wouldn't be impossible to implement. Maybe it would only reflect online donations but still...