This is going to sound a bit Machiavellian. Ask around and befriend a really crappy person that everybody avoids all the time. Someone who doesn't have a filter

This is going to sound a bit Machiavellian. Ask around and befriend a really crappy person that everybody avoids all the time. Someone who doesn't have a filter and is proud of "telling it like it is" but is infact an a... Then bring this up with them. They will tell you the truth. Also, do you suffer from low self-esteem or are otherwise needy? Needy people are human repellants and other people can smell it a mile away.