Muzzle size/shape is inaccurate, even in the show there are male characters with "female" looking muzzles and female characters with "male" looking muzzles.
In order to be accurate characteristics need to be consistent.
The typical attitude on many MLP images is that is it's a female character on the show, it should be tagged as female.
That is not TWYS, and is not an accurate tagging method.
I am sorry if it somehow offends people that a female character is tagged as ambiguous_gender, but we aren't tagging characters, we are tagging images.
Updated by anonymous