Facebook can earn you Tesco Clubcard points

Katie Collins/PA Wire/Press Association Images

Tesco has announced a trial, to enable Facebook users to earn Clubcard points by using Facebook to 'like' and 'share' products they like the look of on Tesco Direct. If their friends click on the link and end up buying the recommended product, you both earn the points.

So is this a brilliant example of getting something for nothing, or is there a catch?