They are bots, scams, etc... I have them come across my skype with the same starting line "Hey, I'm new to Skype and found your name in a search and want to be friends. blah blah blah..." All the same, test them out and they'll all respond the same somewhat, throw in a few testers, they won't know how to respond to it then begin from square one again "Heyyy!" It's annoying. You can report, but I highly doubt Skype gives two shits, so just block them. I currently had one add me as well, I do a reverse IP lookup on them, a reverse image search on their pictures etc and gather all the information I can on them, then just block their IP as well.