Facebook, Google, twitter, etc. They all have their OWN USP. Therefore there is no black and white "this is better than the other." It's about what you have and who wants it... and where they are/how you position it.
So specifically:
From my own data, Facebook isn't totally ineffective and it is not a "waste" of money nor are the people unqualified, if you are strategic in your approach. A super targeted campaign is likely going to determine your end result.
However, it is not dependent upon interests or "fan page likes" alone.
I highly recommend creating custom audiences of people who you know are most certainly in your target demographic and put some creativity into creating the group.
If you do this, use the optimized CPM option in the Power Editor to an audience of around 3K-5K.
Just as a testing example: Taking this approach, I paid $3.81 for 3 front end sales, 11 leads, and 7 phone numbers. My clicks were up over 270. I would have paid much more had I bid on clicks to a broader audience.

PPV is also another good option for pushing a skin care product to a specific target demographic that is already visiting other high traffic sites relevant to your offer.

Just an extra 2 cents :)
Youtube leads cost me a fraction of what Facebook leads cost with a great campaign. You are lucky to get quality FB leads for $2--$2.50.

Pinterest and Twitter are geared more toward the age range and income level that most skin care products are relevant to.

Forgive me for the scattered insights, I'm working on cup of Coffee number 1 this morning. :) Have a great day