What the legal position on bands using someone elses intellectual properties to promote themselves?

We've all probably seen bands taking images from famous cartoons, TV shows, celebrities and stuff to put on t-shirts and flyers and stuff, but what's the exact legality of it? My mates band is currently pressing some records to vinyl and pre-order bonus is some screenprints of various Simpsons' characters.

This isn't a free flyer or something so they're basically charging money for something that isn't their property, because another artist has made this, so like...it seems as if they could get in a lot of trouble for it?

Same with people using Breaking Bad on their band t shirts and similar stuff like that.
It is illegal, obviously. You need permission to use somebody else's intellectual property, and when famous bands do this they typically have permission. Lately there have been exceptions, when new generations of 'graphic artists' etc. have googled images of stock stuff for a quick paycheck and ended up getting caught (Bring Me The Horizon, for example, had a huge thing on their Facebook page a few months ago because some artwork they'd been using [unknown to the band, I believe] had been lifted straight from an online portfolio of a model, with some minor changes made to the image, and the model found her image used everywhere and, rightfully, went ape shit).

If they're doing that, and sell enough units for it to actually be seen by many people, they're idiots walking blindly into a whole shitstorm of potential legal issues. That is, assuming they don't have permission for the images (which, with Simpsons images, is doubtful).
Hey, look. Sigs are back.
They could get a cease and desist letter, ask for royalty's or threaten to sue.

Most likely they'll sue.
Most of the important things

in the world have been accomplished

by people who have kept on

trying when there seemed to be no hope at all
Smart people pay for the use of other people's property. Morons don't pay, get caught and sued. End of story