But what are the signs that I should look for to find out if she is only interested in marriage for the papers?
I assume youre not very good lookin if u have that kind of doubts
Even if that turns out to be true (and i think it is coz u met her through friend who set u up and probably leading role in that had his polish girlfriend/wife) when your wallet is fat enough she wont leave you unless u make her to with your own behaviour
im a Pole and i can assure you that most girls here (not all of coz) are looking for a nice (not particulary good lookin) man with a good financial backup and if u have that u'll be okay plus living in the US is another incentive for her (and her family :) )