ok here i am back with some new information that might help the case
apparently, stubby and shotgun are the only ones affected by this, spaz is not really affected like them, still some shots may miss but i think it may be blamed on the fact that this bug exists at all.
after a long research this is what i found:https://www.youtube.com/watch?v=9S3XXCI8N8Q
the probability of shotgun repeated crouch is 0%, as you can see, however some c-glitch shots may actually be received, 50% of them at least..https://www.youtube.com/watch?v=ZWExn-gY_oo
the same with stubby, however this weapon does not require glitching at all to be played with, it's only problematic when you try to double shot with crouch, which is indeed frustrating.https://www.youtube.com/watch?v=SZi5-egbQek
however as i expected, spaz does a much better job with this. as you can see this weapon does NOT get affected almost at all by this annoying bug, since its accurate shots are 95% (both crouching and glitching), due to the fact that this bug exists, however it's not really affected that hard
so you might want to revise the shotgun and stubby, and improve the gameplay for everybody.
the question is, why is shotgun most affected?
simply, it's because this weapon often requires a ton of crouch spamming in order to hit a target, due to the fact it has same bullets spread as the spaz, but longer range.
stubby doesn't require because its shooting anim is way shorter than shotgun's, and because in a close range you don't need to spam crouch that much as i see.
ps: switching to fist ( the null switch as i call it ) makes it even worse miss shots@Piterus
may know since he played in his own servers /dm stubby arenas, and might have at some point noticed his shots are just desynced totally.
in conclusion: for perfect gameplay and non missing shots, play with spaz until this bug is fixed
stubby will work out too if it's not spammed ( not required but may be preferably to do so by many old players)
avoid shotgun fights, you will never be able to get absolutely accurate results, because this weapon in usual gameplays is totally bugged:https://www.youtube.com/watch?v=1JTPXshuNK0@AdTec_224
i'm waiting for an answer as soon as you're active, or at least take this topic into account and manage to deliver an update in time this summer, i'd love to play with everything fully working, and i think everyone here would prefer the same.