I love funny TV commercials and even though I can recite the commercial later - I don't always remember what the ad was selling. However, the goal is for the product to be memorable - not just the ad.
Does humor really increase your sales? The stereotypical salesperson is usually funny, wouldn't you agree? He/she has a good personality, is outgoing and knows how to get a laugh and when to laugh. But I believe there are certain businesses where humor can decrease sales such as:
Financial services
Accounting services
Medical facilities
Physicians (except maybe a pediatrician!)
Mental health services
Banking institutions
The above businesses are dealing with serious or confidential issues. Customers may interpret humor as too casual or informal for the the private nature of the services being provided.
While humor is a way of creating common ground with others and diffusing conflict, it has to be used properly. Stay away from:
Off color language
Racial or politically charged humor
Gender-biased humor
At the root of why funny people sell more is that to be funny - you have to be smart, quick-witted and able to process information quickly which are qualities of successful salespeople. Good salespeople understand the importance of timing, which is also a key element of being funny. But mainly, funny people sell more because they are better looking which causes more people to buy from them. (Did you catch my humor? Bloggers can be funny too!)