Is there any way for a merchant to find out the limit on my Amex or Visa cards? People say Amex has no limit, but I know even Centurion has an unspecified limit. Also, is there anyway for them to tell that mine is a secondary card and its under my parents' account?

I believe there is no limits on Amex. You can go out and buy a car with it. The only thing Amex will do is to have you verify that you do have the cash in the bank to pay the full amount when the bill comes. They will ask to you to call your bank and have them verify your balance.

As far as Visa and Master is concerned, I don't think the merchants care about your limits. As soon as you reach your limits, your card will cut you off anyway.

They cannot tell if that is your card or not, unless they call Amex or Visa directly.

__________________
95 R129
04 Infiniti G35.5 BS
10 X204