I love the "redirects" this topic seems to be getting in regards to honesty from one trans person to another.
"Trans people clock extensively."
"Trans people are always looking."
"We have to support each other so I'm not going to be honest."
Let's keep in mind that there are not a chosen few who are the "judges" of passing and well, darn it, we're stuck with their opinions. The people who post their pictures on these threads are asking other trans people for their honest opinion. If they wanted the opinion of cis-people, I'm sure they'd ask them. I find it completely amusing reading the many responses as to why honesty within the trans community cannot be valid in terms of what "real" reaction they will received from the general public.
Here's how I feel. If you don't want to be honest, fine. But if it were me asking for opinions and every single response I read was, "omg you pass", I'd be a bit skeptical. So if honesty is forbidden, I'd recommend adding a disclaimer to each response saying "just trying to be nice!" We are all grown ups, so if someone says they want blunt honesty, I'm pretty sure they want blunt honesty; if they get defensive over certain comments, oh well, that is their fault for asking for honesty.
As for the discussion of being unable to comment whether someone passes or not based off a photograph alone; no, it cannot be stated as a certainty that in any and all situations the person will pass. But, if I comment on a photo, I make sure to include the words "judging by this photo" before I share my opinion. This way, hopefully, it is implied that perhaps in other situations, photographs, videos, etc., my opinion does not necessarily apply. Furthermore, I don't know as I didn't care to look, but if the people who are saying they'll never be honest are the same ones saying you can't judge by a photo, I find that a bit redundant; it would seem to me it could be audio, video, a thousand pictures from all different angles and lighting or even a real-life meet and greet, and the truth would still never be spoken.
Anyway, that's my rant.