When purchasing anything of significant cost, one likes to understand a bit about the seller. In the case of a motorhome or many of its accessories, the personal commitment involved makes this even more desirable. So, on balance, I think the forum is a good way of getting to know a dealer in the first instance.
Most businesses today are trying to move beyond the simple 'push' model of advertising: i.e. they push messages at you and hope to get you to respond. They want to develop two-way interactions so they can get feed-back about what customers really feel and how they are likely to behave in the pre-purchasing, purchasing, and post-purchasing situation. It's an over-used term in marketing, but the name of the game today is 'engagement' not advertising.
I think there is value in having trade members of the forum. It shows a commitment to understanding their customers, not merely selling to them. From the purchaser's point of view, there must be some security in knowing that they are buying from a dealer who is openly accessible and would not wish to become the subject of negative conversation amongst a highly motivated community. And herein lies the rub! The value of the system depends upon the goodwill and pragmatic behaviour of all parties. It is no good if the forum becomes a soap-box for ill-considered ranting. The first recourse should always be to individual discussion, not public pillorying. Thankfully, we do not see too much of that on MHF.
One final point, I think it would be a good idea to have a membership category of 'Trade Member' which appears in the poster's profile at the left of each post. (Nuke, if this already exists, forgive me, but I have not noticed it.) I am sure all genuine traders would be happy to be seen as such 'at a glance' although I accept that we know who most of them are anyway. But it would be a good idea going forward.
Philip