I don’t see this really being a problem either (it’s normally obviously fine or obviously spam), just thought that it might be good to have the rules stated somewhere in case the situation arises.
If a company who sold say cycle computers came on and just created a post to advertise their products, would that be OK?
Would it be OK for them to do it in a thread talking about measuring speed? Would it be OK for them to do it as a post in “trading post” with a sale link? Would it be OK for them to do it in unicycles and equipment?
A special category for industry accounts sounds like a good idea. Some other forums I’m on also have an additional icon over the user picture to make it clear that they’re representing a commercial entity.
That would be less clear cut for an account like Roger’s though as generally he’s on talking as himself, but sometimes he’s talking as UDC UK.