A repeater jammer was located the other night, totally unlicensed but had the gear he needed to get on the air.
Someone pulled up out in front of his house and gave him 300mW on the output frequency with PL enabled, described the cars in his driveway and told him where he should put his radio...or someone would do it for him. Poof, the interference stopped.
It isn't hard at all to find people doing this, it's a matter of having the time and people to go get them. HF is harder than the higher frequencies, but it too can be done.
The shame of it is, you can't have these people jailed for it. So short of removing their arms and sewing their mouths shut, it's something that will always happen.