If you aren't using a new address for every transaction, then you aren't using properly.  Joe shouldn't know your address unless he sent you bitcoins.  If he did send you bitcoins, he should only know the address that he used to send those bitcoins to you.  If you are using a new address for every transaction, this means that Joe will only know how many bitcoins you have at the address that he sent to (which is only the bitcoins that he sent, and so he should know that info since he sent it).

If you aren't using any sort of "shared transaction" mechanism to blend your inputs with others, then it is possible that Joe might be able to link your bitcoin address to a few of your other addresses, but with a minimal amount of effort on your part he won't be able to be certain exactly how much you own and which other addresses are yours.  If you are using a "shared transaction" mechanism to blend your input with others than Joe isn't going to know anything at all about how much you have.


Well, you certainly are confident in what you think you know.  Knowing more than "half the people here" isn't very difficult.  If you know how to spell "bitcoin" then you probably know more than "half the people here".  That doesn't mean that you don't still have a lot to learn.  I'm pretty sure that there are many users at bitcointalk.org that know substantially more than me.  I'm here so that I can learn from them what ever they are willing to share/teach.  It appears that you aren't here to learn from those with more knowledge than you, but rather to make grandiose statements about the future of bitcoins based on your personal opinions, and to brag about how much you think you know.