QUOTE (Father Time @ Mar 24 2008, 04:04 PM)

Yes, Sumdac would have seen the insignia. However, he was never expressively told that what insignia a cybertronian carries is used to distinguish Autobot from Decepticon. One Decepticon with some tribal markings would not really warrant any prejudice to others who may happen to carry the same tribal markings, especially when that other one is your friend.
Or, as a real life example:
"All people with black hair are evil!"
- "Dude, I have black hair."
"That means you're evil!"
- "What? Come on, have I ever done anything evil to you?"
"Not that I know, but you're still evil!"
- "I've lend you my car a hundred times."
"Still evil!"
- "I've lend you tons of cash, without any interest."
"Still evil!"
- "I'm married to your sister. You're the godfather of our children!"
"Still, you must be evil. You have black hair!"
again thats only speculation and retcon
to put it another more logical way...
a guy has the nazi logo on his army uniform while carrying around a gun around the time of WW2 he is also rather shady looking and is asking you to not tell any one he is hiding in the city under the guard of the good guys...
"All nazi's are evil! and you have a Nazi logo on your army uniform"
- "ok Dude, I'm a nazi."
"That means you're evil!"
- "What? Come on, have I ever done anything evil to you?"
"Not that I know, but you're still evil!"
- "I've lend you my car a hundred times."
"Still evil!"
- "I've lend you tons of cash, without any interest."
"Still evil!"
- "I'm married to your sister. You're the godfather of our children!"
"Still, you must be evil. Your a nazi! or at least you have some connection and as such give me resion to question you or at least report you"
but thats not whats going on in animated he is only hiding megatron since Sundac thinks he is one of the good guys and that he is ashamed of what he has done to their freind. but now he has proof he is infact connect to the decepticons so he knows megatron is fooling him in some way
now i could go on but its nothing more then a plot hole and should not be retcon'd into a 1000 page rant