Cartoons are supposed to be a show that children are supposed to enjoy, just because some of the things that are shown are not practical doesn't mean that it is bad for them. These types of shows are supposed to let a kid broaden their mind and think outside the box, and then after that they just enjoy themselves. It doesn't do anything to leave any type of negative mark.
Even though I am well aware that times of changed since I was a child as far as the content in cartoons, I still look at them as completely harmless entertainment for children. I think children are smart enough to realize that what they are seeing is just a show and should be taken literal.
Like any television show it really depends on how often it is watched and who the specific person watching is. In general I do not believe cartoons have a bad or negative effect on children. It gives them something nice and light hearted to watch, as long as they don't overdo it things should be fine.