I think the biggest problem with code reviews are that some people can't do them right. For example putting final in front of class/method/parameter/anything doesn't matter and should not be in a code review. Another example is using the wrong loop since only foreach is ok. Require to comment everything. String +/StringBuilder/StringBuffer optimizations. If I got a code review with any of those things I would think that guy is an idiot and if I was not forced to change the code I would not.

Also sometimes code review tools are just wrong, for example default PMD (Java) likes to say that class has too many methods, so what I did is to create abstract parent class and push some methods there. I could have split the class into 2 classes, but I think the API will be easier to use with all those method in one class (it's a small lib and my design decision). Some people will always use just the default, so it should not be crappy.