We recently received test results on one of our ads in Mexico and Spain. It did very well in former but not as well in latter. I asked how big a factor the cultural differences were, and was told that in Spain, they have a lot more commercials than they do in Switzerland or even the United States, making them super-humanly cynical of advertising.
A co-worker who has a house in Barcelona, and is married to a Castilian, confirmed this. He said even American shows that are translated into Spanish have more commercials packed into them than in the States. An episode of Lost is about 43 minutes, leaving 15 minutes for ads and ABC's promos. In Spain, it would probably be 25 minutes of ads, bumping The Unusuals or whatever comes next to a 9:10 start time. (The Spaniards aren't so die-hard about starting on the hour.) They even have short micro-commercials during the commercial breaks to remind viewers, "You're watching Lost."
So all of those spots (including more commercials before and even after movies in theaters) means the public's deflector shields are up the second the AVO beings, "¿Nunca no consiga a eso ninguna sensación tan fresca?" So if you test well in Spain, you've probably got a very good spot on your reel.
(I've also learned that in France, the TV is government-controlled and they've put limits on how much advertising appears per channel, per day. I haven't had anything tested in France yet, but I'm guessing they're automatically cynical of anything commercial, anyway.)