Many salesmen don't think they even need to know a product/service to sell it. I got "trapped" into going to a MLM meeting (I went for the free lunch at a nice restaurant) and overheard a conversation a couple of salesmen were having at our table. One man was asking for details on the products being presented. Another salesman looked at him and said "who cares, it's all sales" and went on to say that it shouldn't matter to a professional sales person what they were selling, only that they could make a sale off the item/service in question.
Pretty poor professional attitude if you ask me. I'm sure he was all smiles and your typical snakeoil salesman when hawking his products/services too