As I've gotten older, I find most of the stereotypes I grew up believing were bullshit and not particularly useful for classifying the subjects of the stereotype—however I do find they help me categorize the people who believe them.

So you're a white dude who thinks black people like fried chicken and watermelon? They do. So do white people because that shit is cheap and delicious. But you're a racist.

All cops are bad? The last few years have been revelatory about a problem that has existed for decades. But you're a moral absolutist and not someone to discuss nuanced issues with.

Republicans are better with the economy/foreign policy? You liked Regan and never grew out of it.

The stereotypes themselves aren't really useful, but understanding the speaker is sometimes helpful.