yes, there is, case closed, no questions asked, it is broken
ummm, how's it broken if I beat the game using them? What is broken about it?
I/O is looking in to updating how disguises work. The makers of the game admit it needs updating. It doesn't matter what your opinion is and whether you beat the game or not. No one is saying the game is unbeatable with disguises - it just doesn't work in a fun way. Videogames are supposed to be fun. Again, doesn't matter if YOU had fun - you're just one person.
Just to reiterate since you apparently need reiteration, I/O admits it needs updating.
The disguise system is definitely flawed and needs to be adjusted. It's not broken but it doesnt work the way its supposed to. Whenever I used a disguise, I would get spotted from across the room wearing the same outfit as the guy who spotted me. I did better NOT using disguises which was a good thing because I prefer to wear the suit and tie anyway.