If you come into a forum that is not pushing any agenda (other than "do it right and you will be rewarded with quality") or, on the surface at least, is not promoting any particular vendor and start lecturing people as to how to make decisions about their purchases by telling them that they can't express themselves the way they wish to express themselves, then you will push away the customers you are apparently trying to salvage. Then of course there are all the friends of the pushed away customers that hear about the defensive lecturing. As I understand it, word of mouth is pretty high up there on the advertising ladder, I'm not sure how it works in cyberspace.
IMO you were on the right track when you called Sluggo up short when he said something to the effect that "once again the bus depot parts are crap". It wasn't your part, you just sold it. Your point was taken and the situation was corrected as I recall. You are now debating, lecturing, and, in a way, criticizing your customers.
Exploring the forums that relate to your business is a good practice. Crying foul when you are fouled, again a good practice. Going on and on about how you think people should express themselves or make buying decisions, and in a condescending tone, no less, not so good:
I can almost hear the whine from here.if you are going to use forum topics like "parts found to be junk" (which is much more strongly worded than on any other forum I've seen), I think this point should be a 'sticky' on those threads. Any single, isolated report on a product that has not been "seconded" by others with the same experience should be taken with a grain of salt, because a sample size of one may not be representative of the product.
We out here in "buying stuff land" are quite aware of what makes us make a final decision on our purchases. Frankly, it's not the sales rep. (or owner of the shop) that has the most influence. If the sales rep (or owner) tells me they were listening in on my conversation and they didn't like how I was talking or going about making my decision, that may help me with the final decision.
I've heard mixed reviews about Bus Depot and will still use my noggin when it comes to any purchasing I do (research the product, ask around, vision quest). When I feel like it, I will whine out loud about how crappy new parts are compared to old parts. They sure don't make 'em like they used to. I might even complain about my achin' bunions.
Stick to observing, absorbing, and clarification. Leave the lecturing for those seeking a lesson.