Spam is advertising by people who want you to buy the product from them. Few people regard advertising copy as honest, so technically it violates the rule against trolling. We're all free to talk about why we like our cars, musical instruments or other possessions, so long as we don't work for the company or have any commercial interest in its prosperity. I don't start threads urging you to hire the company I work for to build your software. I have occasionally offered my services as a professional writer and editor, but I do small jobs for my friends for free so there's no profit involved. I think the Dyson is a great piece of technology and I'm happy it was invented. Honest testimonials from customers--happy and unhappy--are one of the best resources available when shopping. Several criticisms of the Dyson were posted on this thread so it has become a rather balanced review of the product. Sounds an awful lot like proper science and scholarship to me.