Soooo it has been reported that there are some fake World Cup stickers being traded for real ones. 
This will not be tolerated on the site please report people using feedback (link below) that do this, and demand proper stickers or compensation back.

How do you avoid receiving these stickers?
Swap with people who have good feedback, or demand stickers to be sent to you first if you are worried. ask for photos maybe if you are concerned.
Swapstick members who have been here longer can ask for stickers to be sent by the junior / newer  members first, and can then send their stickers back afterwards.

How do you spot fake stickers?

There are a few signs that they are fake:

1) badly cut edges so that the borders are bigger on one side than the other

2) Sticker pictures are fuzzy or off colour

3) background peeled off bits are wrong colour or size

4) bad spelling or numbers on the stickers