This certainly won't be any surprise as over the past decades even many players admitted they used something. There are also a lot of examples FIFA ignored positive doping tests as mentioned. This article
mentiones some cases FIFA did. Recently one of the Voetbal International reporters asked to himself in his column: we can ask ourselves: does football want to know they use doping?
It appears they don't want. Reading all kind of articles about doping it looks to me that doping has been used all over the world. However, tests in cycling and athletics are much severe as it is in football.
Most recently we have Operación Puerto in Spain which also involved football. Dr. Fuentes has always told his clients were not only cyclists, but also some famous tennis players and footballers. The legal authoroties in Spain have already destroyed the blood samples, something you don't do if you have to hide something. Fuentes promised he would reveal some names by the end of last year, but he did not. Real Sociedad admitted they were client of Fuentes in the 2002-08 years.
BTW if it will turn out Spanish football used doping in recent years, I won't believe they were the only ones.
The remarks made by former Ajax doctor Rolink in this post
is as clear as cristal.