This situation has happened to me before several times:
A "new" player asks me if I would help him, teach him how to roleplay, or invite him to my guild. The player tells me he is new to the game. I waste huge amounts of time with explaining and teaching. In the end I find out that the player is someone who has played PS for a along time already.
This is annoying and disappointing.
It may be good if someone does not know about who the player behind a char is. Sometimes it even helps if you do not know the other players chars/alts. It can help you to judge the char and player without being biased. But please: Do not waste other players' time by making them tell you about things you already know just for the sake of giving the impression that you are a noob.
If you insist on not giving away who you are (or who your other chars are), I recommend that you do one of the following.
1) Simply say that you have other chars and know how to play, but that you do not want to tell about them because you want to keep the RP without bias/influence. I did this myself sometimes and the other players understood that. If someone does not respect this, they are not worth playing with, because they obviously have other goals than enjoying the game as it is meant to be.
2) You lie that you did not play PS before, but you played other MMOs, RPGs, etc. You can also add that you read the forums and already know a lot of things because of that.
3) You lie that you played PS a long time ago, but you forgot a lot about it. You did not forget how to roleplay, but you do not know the players/chars. This at least prevents other players from wasting their time by teaching roleplaying.
So please:
Do not waste other players' time by playing the noob!
If necessary lie, but do this in a way which does not waste time (yours and others).
Thank you.