When I was getting my career going in Denver, Microsoft used to host lunch sessions every few weeks in their office. There were some Microsoft employees presenting and some community members. I learned a lot from both groups. At local user groups, more often than not, a community speaker was present, but there were plenty of people that worked for different vendor companies that delivered talks. I saw many of these people are knowledgeable in their area, and they taught me things I used in my job.
At some point, it started to seem that presenters that worked for companies weren't experts, and maybe more importantly, they weren't worth listening to because they were "selling something." In fact, a large community conference, and some small ones, banned "vendor" talks and the use of tools in presentations. Sometimes even free ones, if someone was promoting the software as the focus in their talk.
That hasn't applied to Microsoft, even when they are "selling" something, free or not.
I understand some of the concerns. I've seen some extremely poor presentations from sales and marketing staff, who often don't really understand the technology or why it would be used in one situation over another. There is no shortage of complaints about the poor experience from the attendees who didn't learn anything useful.
There was a post about this topic from a writer. While I think lots of larger technology conferences do end up with speakers that vendors sponsor. The SQL community might be slightly different as we have lots of community speakers, more than I ever imagined we'd have. I love that so many people have chosen to get up in front of groups and share their knowledge.
Technical experts abound, and many of them work for vendors. In fact, often the people who give high-quality technical talks get hired by various vendors. I'm one of those, and it's always a challenge to find a way to talk about a problem and potential solutions without selling a product. I must present well because I rarely get complaints. I find there are a lot of other technical experts that do a great job as well. I hope that you give most people a chance and if they end up making a sales presentation, then let the organizers know. They can always address issues in the future.