We sometimes charge for sponsored Q&As - they are one of the revenue streams that allow us to run a free-to-use site. Often Q&As are part of a wider promotional campaign that we're running across the site. We always say in the opening post when a Q&A has been sponsored - and by whom.
We will only host Q&As that we feel will be of use to Mumsnetters and we would not host a Q&A with any individual who we didn't feel was qualified to answer the questions.
We always ask the respondent not to promote the sponsor's products too heavily in their answers. We aim to post the answers as they are sent to us but we do have editorial control and would not put up answers that were full of plugs for a company or product. We send over a maximum of 20 questions, which are chosen by MNHQ which we feel are representative of those on the thread.
We do also run Q&As that we don't charge for and when this occurs we will make it clear on the thread.