Re: marriaying for citizenship
Similar questions have been asked before on this forum.
Marriage is a reason itself, if somebody whos got other reasons, that will not work.
So how do we know about the ingenuity? This usually comes very easy through deductive psychology, however only scenario where it will not work is when guy/girl is fairly different from their family and were genuinely interested while family gave away wrong signals, or vice versa (family were genuinely interested, while gave the right signals unintentionally masked the wrong signals of potential partner)