Most definitely
Personally, I've never clicked an advert on facebook, and don't plan to in the future.
I think Facebook's real strength lies in its ability to build and communicate brand information to huge numbers of consumers.
But I imagine big companies will soon wise up to the fact that the ROI is not there for real advertising.
General Motors announced just before the IPO that they would no longer buy advertising on Facebook. Other companies will follow suit.
Also, as people become a little bit more IT savvy, the effectiveness of marketing on Facebook will diminish.
e.g. If I click on a "like", you don't know my full name, age, sex, address, school, home town or phone number. I choose NOT to share ANY personal information like this.
As people wise up, what will companies really gain from knowing 500,000 anonymous people like Kit Kats?
Advertising for Kit-Kat is about brand awareness. The more people talk about Kit-Kat the more they are likely to buy one. They do not need to direct market their product and Facebook is perfect for them because everyone is on it, especially those who are most likely to buy sweets.