I think just like people, cats are so different and not one is alike. We have 2 cats and have had many cats over the years and we have never had the problem with them being mean because they are spoiled. I think cats in general are and feel entitled though. That's a given.
My cats are extremely spoiled... oh so spoiled!!! They are both loving and cuddly. They sleep with us and seen quite happy most of the time. I guess we are blessed.
Like I mentioned though.. all cats are different so spoiling one may be fine but if another one is spoiled I'm sure there is a possibility it could end up in a disaster!!!
We have 2 cats and have had many cats over the years and we have never had the problem with them being mean because they are spoiled. I think cats in general are and feel entitled though. 
That's a given.
