Many times transphobes try to invalidate transfems by calling us "a man in a dress" or "a man with a wig" to imply that it's a low effort trick done in order to enter gendered spaces and do something nefarious.
I think this line of argument is only successful among people who have no idea how much effort the average transfem puts every day into just being herself. A cis man with bad intentions would never go through so much trouble.