A bunch of people haaaaaate Homespun, because a) it's bad to learn on (and tends to be in stores where beginning knitters would be buying yarn) because it's so fuzzy (you can't see what you're doing), it's easy to accidentally split, and it's really hard to knit if you knit it tightly (as new knitters often do), b) it's acrylic, fuzzy soft acrylic, but still acrylic, c) it tends to worm (bits of the yarn slide around in the knitted item so you have little loose patches and then little tight patches), and d) a lot of people try to make things out of Homespun that should not be made out of Homespun. On the other hand, their colorways are generally pretty, it is pretty soft, a lot of people don't have problems working with it, and if you pick the right project, it will look just fine.

People also haaaaaate Fun Fur (feels horrible, instantly makes anything look like a skinned Muppet).

Lion Brand also gets some blanket disapproval because you can often get better yarns for similar prices from actual yarn companies/stores. On the other hand, you can't get those better yarns at your local Craft Barn or SuperMart, so they do also make decent yarn available if you need it immediately, or for those that can't/won't order yarn online, or for areas without a yarn shop.