I was thing, if a person came on line and had a user name "egg roll" and as an avatar had a picture of an "egg roll", would we all assume this person was Chinese?
What if the person was really a White Anglo-Saxon Protestant.
Would this be called deception?
Would this be lying?
Is it sin?
Is deception sin?
I think, in a way you are right. If you are expecting to be served an egg role and while you are having it, you finish a half of it and then you discover that it is not really an egg role!
If you want that situation to be calm, then you might have two options:
1. continue to eat the remaining while looking at others around you, eating them normally.

2. stop eating it and throw the rest in the trash and never visit that place again.;)
There might be members who might not reveal real information about them, the internet being an insecure communication, depending on the threat they might have in their part of the world. It can sometimes be difficult to understand if the person is a minor or elderly. I know how elderly people interact, so I can understand even if they do not provide their age. Just in case if the person is a minor, if we know then we might be more patient to help them understand what we say.:)
If the person is not a Christian and trying to find out what is happening here, I'm sure they might either like Christian religion or they may not understand anything because the wisdom of the Word of God is given to them who believe in Jesus.
If there is any who is trying to mislead others, then Jesus tells us that we need to be careful:
Matthew 7
15 Beware of false prophets, which come to you in
sheep's clothing, but inwardly they are ravening wolves.
16 Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?
17 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
18 A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.
What if you find a genuine Christian in these forums? Would you like to have fellowship or communication with him despite of the limited information he could provide about himself?
Lets follow Jesus! :)
All Glory to God.