I can't stand assumptive people

Why assume something when you can just ask? Why formulate an opinion about someone based on your assumptions when you can just ask? In other words I can't stand assumptive people. It's a shame that people are so quick to assume things about others especially negative things. Oh he doesn't like me because... Or she doesn't like me because... When the truth is you're the one who doesn't like that person but you just come up with reasons to convince others or even that person doesn't like you when you're the one that doesn't like that particular person. It's annoying they're annoying and I can't stand assumptive people because they base their opinions on a person without any facts to backup what they're saying.