The former Chair of our local CRFG chapter wrote
this.
I can attest that they are useless. What isn't useless are traps. Traps are only as effective as the mind behind them, as most need at least some modification/ technique to be/remain effective, so I highly recommend studying up on the techniques mentioned in the link above.
I personally have found the Squirrelinator to be very effective when modified/ used skillfully. The basic problem with it is that the springs that come with it to hold the top shut are too weak, and need to be replaced by wire. The technique is to keep it in a place that isn't immediately visible, so that they don't learn when their friends get caught, and to empty it soon after they enter. I bait it upside down for a few days to get them used to it, then I will flip it and catch them and afterward change locations. Failure to meet any of these points seems to only make them smarter at avoiding capture.
The holes on this trap are too large for rats, and rats will eat all the bait at times. I have heard they also make a Rat version with smaller holes. I have had great success with electric rat traps, and have heard great things about the old-school spring type ones when attached firmly to planks set against fruit trees.
Good luck, and invest in some legitimate solutions.