Al Gore represents a certain class of people that advocates and gets rich doing it.
The fact that he get's rich from it will always cause those that oppose him to question his motives. Is he doing it because he cares, or is he doing it because he wants to get rich?
In the end the money is a small factor, the questions everyone should be asking is, is he right about the things he advocates for?
I don't follow him that closely, but in some of the "global warming" stuff he did I think exaggerated and left crucial information out that uneducated listeners wouldn't miss and would draw vastly different conclusions based on inference.
The best example I can think of is when he stated "if 1/2 of Greenland were to melt"...And then went on to show how sea levels would rise by 20 or so feet and what the impact would be. What he left out is that it would take 1000 years for 1/2 of Greenland to melt, even at the most aggressive projections.
Personally, I cannot condone doing the right thing the wrong way. It misleads people and gives the other side ammunition.
Al Gore is not a scientist. He gathers information and he presents his interpretation of it.