The ads need to accomplish what the goal is- so if the goal is simply more likes then the ad sequence needs to be designed to accomplish getting more likes. If, however, there is a sales goal then the design should be very different- specifically created to generate sales. If your intent is to generate sales and you are getting mostly just likes then your ad creative needs to be rethought and redesigned.

We have built one client's Facebook page up from just over 100 likes to over 5000 now and have recently begun creating ads to generate sales for them, but this has been part of a long term strategy for the client.