I have discovered that fructose is a problem for me.  It may be a problem for others also so I am posting this message.  I recently cut out and minimized all foods with fructose and fructons. I am eating meat/fat, tubers/squash, leafy greens. My face cleared up, I feel better, and stubborn weight is coming off. My carb level is less between 50-100 grams a day. 
I think that some of the Paleo failures MAY be the liberal use of fruit as a carb source. Once we left Africa fruit was only available a couple months a year. Drying fruit is a mess without technology. 
In my bouts with acne and rosacea, I tried everything under the sun. Sometimes it was clear sometimes I had breakouts on a paleo diet. My dermatologist said it was an immune issue.
Long story short it seemed like a liver issue.   Fructose seems like a liver toxin! Great explanation of the science.  http://www.youtube.com/watch?v=dBnniua6-oM. 
The question is how much can you fructose can you handle. For now I am trying to keep it as close to zero as possible.
Frequently you hear low carbers say a calorie is not a calorie. The truth is a carb is not a carb also.
I just discovered (yesterday)a Blog/website that may give anyone interested more info,   http://theprimalparent.com/2012/03/31/ibs-depression-skin-fructose-malabsorption/
Again, this is my experience,
-David