[evilnumberlady]

I think it would depend on some unknown factors.

Do they sell animals from a breeder in addition to the "dumped" pets?

Is there an adoption process or can any person take them?

How well-cared for are the guinea pigs?

If you could get that person to answer these questions and decribe it in more details we might have a better idea.

At any rate it's at least better than the more average method of stocking animals, but I doubt it would be quite at the same level as adopting from a rescue.