Photo digital signature - how reilable is it?

I'm trying to trace some photos I've been sent. More recent photos seem to be on different cameras. So this person uses many cameras? If on a tight budget, that seems odd, yes?

They include:

Canon Powershot A410
Nikon D90
Canon EOS 500D

Added (1). It includes camera model, date taken, size, graphics type, is that EXIF?

I really do not understand the question at all.

Are you talking about the EXIF information?

Can it be changed? Yes, but most people don't know how and/or don't bother.

What does it really matter if the person is on a tight budget? Unless the person was borrowing money from me, I could care less how many cameras they had. If they were borrowing money, then I would take a camera for collateral until I was paid back.

Yes, camera model, date taken, and size are all part of the EXIF data. It's pretty easy to change it if you know what you're doing. That's why a lot of people recommend using newspaper headlines to establish a date in photographs taken to document an apartment's condition, for example. You can falsify the EXIF data, but the newspaper in the frame proves that the photo wasn't taken before that date.

I'm on a tight budget, but I have five cameras and quite a few lenses to go with my SLRs. If you're really passionate about a hobby, you find ways to work around budget restrictions. The only two cameras in my collection that cost me more than $15 are my Nikon Coolpix point-and-shoot, which I bought several years ago, and a Nikon D90 that I spent several months saving up for. With my three film SLRs, one was a gift and the other two were purchased at Goodwill thrift stores.

The only thing that I find odd about that EXIF data is that the photographer might be switching back and forth between the D90 and the 500D. Usually a photographer picks one system and sticks with it for lens compatibility. Having both a Nikon and a Canon means you have to have twice as many lenses. Of course, it could be that the cameras used to take some of those pictures were borrowed from someone else.