I'm pretty sure it's a problem of perception.
The one performing juggles or shooting projectiles tends to not feel the lag. Of course, they're just doing inputs ahead of time, and hoorah! Their moves look just like offline!
The one GETTING juggled, or DEALING WITH projectiles... not so much. The person on the defense will always "feel" the lag worse than the person on the offense, since they have to worry about defensive manuevers.
Eeeeh, perception does come into play, but the individuals I mentioned are people I've known for quite some time, so I know what they can or can't play in. Especially S.Snake--I know him in person. Now, I'm not saying one guy can have near-perfect connection and the other rubbish, but there's a noticeable difference. For example--
Player A has lime-worthy connection.
Player B has yellow-worthy connection with occasional frame lag.
Now, I
don't think it's possible for:
Player A has green-worthy connection.
Player B has red-worthy connection with much delay / frame lag.
Then again, the answer to this topic might be the same as that age-old question:
How many licks does it take 'till you get to the center of a Tootsiepop?