There are also yet others that are far more vague - Jews are trying to take over the world - blacks cause all crime - and all Mexican's coming to the US are rapist and drug smugglers.
I believe the vast majority of these people aren't evil or crazy people. They're just people on the right who are deeply misinformed by Right Wing propaganda and a political system that far too often uses fear to manipulate it's members.
The first things you mentioned I can't see causing people to have fear or hate of a group of people. But these ones can. Also I see left wing propaganda within this comment as well.
On blacks....causing ALL crime is not true, but well beyond proportion to population is. But politically, haven't heard any political reasons to bring it up, other than answering why they are disproportionately arrested and jailed on the claim of racism from the left propaganda, as if it's all for smoking pot and whites are not arrested for that. But on the statement itself, you only need to look at arrest statistics, and look at what the arrest was for. Blacks are arrested for crimes out of their proportion for theft, robbery, murder, etc (smoking marijuana and victimless crimes would not count, people generally only care about if a person will commit crime against them or their family). Not all crime but well beyond proportion. My own observations though, it's not the color of skin, meaning not ALL blacks would figure into that percentage, only the thug culture ones. Just like with white people, you can see good ones and trashy ones on how they conduct themselves and dress. I would not feel at all uncomfortable having black neighbors, I've dated a black girl, and have black friends, but I would not feel comfortable around thugs nor have them as friends. Even black people don't like them. You can also go to spotcrime.com, I live in an area that before my time used to have sundown towns. There are neighborhoods where only blacks and won't be able to really find a white person, and neighborhoods predominately white. Without telling you where they are, on spotcrime.com, looking over the geographic area, you'll be able to tell which neighborhoods are which, and the crimes are not arrests for smoking pot, but crimes with victims. In areas without ghettos though, or without the thug culture, I expect that blacks are no different with crime than anybody else.
For Mexican's, there is no, "ALL Mexicans coming LEGALLY into the US are rapist and drug smugglers", it's that many SNEAKING IN ILLEGALLY are criminals. It's left wing propaganda saying right wing people say that ALL Mexicans are criminals. People say people can fly in and overstay their visas, so why is south border worse? To fly in, you must passed immigration, have visa, the government knows who they are and if any criminal background/issues that would prevent them entry. Sneaking in, have no idea who they are, or if they are a danger and wouldn't ever be allowed to be admitted, even if they had a visa/passport. Big difference. Nobody has a problem with Mexican's legally entering the USA.
