Why some people think mexican illegals are all child molestors and criminals?

i was looking at you tube and there was a lady talking about diseases like TB coming from mexico with illegal aliens and saying most of them are child molestors and then came to yahoo answers and found the same opinion from a lot of people, i was born in Mexico and lived there for more than 20 years and i only saw one case of child molestation by a school bus driver (guess what, he was a retired american living in mexico) , we have child molestors in mexico but most of them get killed after they molest a child, Mexicans do not have a tendency for pervertion more than what an american can have and you have to be a looser of epical proportions if you think that the lack of green card inserts a special chromosome in your system that instantly makes you a child molestor. the other thing that chaps my is the saying from some folks that illegals cost a lot of money to taxpayers, is that right? i do not think so, most illegal immigrants are nice, humble, hones st people trying to make a living and most of them pay their bills and taxes and non of them get a refund like us THEY DO NOT GET A REFUND, THEY ALSO NOT GET ANY KIND OF GOV AID LIKE WELFARE OR MEDICAID, THEY CAN NOT GET IT, i am glad they can not get it , it would not be fair, but quit lying about the cost of the illegals, make some research about who is making those statistics and you will see that they are also racist so we will not be ablo to believe in a statistic about illegal immigration until somebody impartial and independent from any racist argument make that survey, so please, think about it twice before judge one of them and do not go by one opinion, always look for the other side of the coin.