ooking for a partner abroad is not any different than any other search - search for a house, a second-hand car, or whatsoever, in one simple yet important detail: there are always will be people who will try to make you in.
The history of marriage scams started ages ago, and it's not Russians who invented them.
I remember a story of American author O'Henry about the legendary scammer Jeff Peters who practiced his skills in matrimonial industry long before the Internet (I read it in grade 6 - of course, in translation to Russian).
To refresh your memory, him and his loyal friend Andy Takers decided to organize a low risk venture by placing an ad at a newspaper for singles: "Wealthy nice widow is looking for an honest kind man who will take a good care of her and her capitals.
There are usually sequences of letters, and they send the same messages to all their correspondents, one by one, making the only change - the man's name (usually it appears only once, or does not appear at all - *she* uses "sweetheart", "my love" etc instead).