Trolls often have clear title to a patent that covers something. Many of these patents should not have been granted, but they were. If you fight them to the end

Trolls often have clear title to a patent that covers something. Many of these patents should not have been granted, but they were. If you fight them to the end, you can often get the patent invalidated, but the trolls are smart enough to settle before that happens. But they generally don't have a patent that covers anything real. Even ignoring the situations where the patent is indefensible through defects in process or due to prior art, the claims in these patents often don't actually read against the businesses being sued. The problem is that it takes tens of thousands of dollars per patent to get an opinion from your own lawyers about whether the patents bear on your products or processes and you pretty much have to do that even if you never go to court.