Oh I get it now, they think we're poor and pathetic and we need the gifts, but if we're an impressive race we are obviously doing well for ourselves.
The racists.
I guess we'll only discover when we get the creation kit.
Personally I think it's quite random and just tracks if you finished a quest for them, if yes, then you have a chance to receive a gift.
---EDIT---
Funny thing I can't marry Ysolda (don't want anyway) from whiterun with my orc, my Imperial could, and they both did that quest for her (tried reloading the game and reenting the city and still the same result)