That's mostly what I get too.No luck yet people just show me all the shinies they have then they leave.
I got most of my luck when I first got White, random folks would trade me high level Pokemon (That I later found were common further in the game) for Tympoles and Blitzles.
My best luck was when someone traded me a Lv. 50 Dragonite for a Seviper. The Dragonite is still #1 on my team.
I also got a shiny Ho-oh for something I can't remember. I later found out it was hacked, so I traded it for a legit non-shiny Ho-oh and a clone of it for a shiny Hydreigon.