Well, not all of them.
Those that create tons of structs for datatypes and even more functions to work with them.
I hate them because they almost look like sane OOP APIs but are awfully to use compared to
what real OOP languages would offer
Consider this example:
CFStringRef cfstring =
CFStringCreateWithCString(NULL, "http://wwwkde.org/", kCFStringEncodingUTF8);
CFURLRef cfurl = CFURLCreateWithString(NULL, cfstring, NULL);
// use the URL