As a salesman myself, I agree with Ucmgr. "Rule #1: The customer is always right; Rule #2: If the customer is wrong, see Rule #1." All customers feel insecure, because they believe that they need or desire something, but know that they'll have to pay to get it, and therefore worry that they'll be taken advantage of. This insecurity can lead to some spectacularly squirrelly defensive behavior, and we are all susceptable to it in some degree. All sellers need to understand that this is just an inevitable part of the terrain, and be prepared to handle the results of this psychological fact with an equanimity which stems from the realization that you are actually more dependent upon the customer than they are upon you. The web's greater anonimity certainly plays a part in reducing the sense of obligation or inhibitions toward discourteousness in a sales interaction, but the fundamentals of the situation are nevertheless unchanged.
There will on rare occasions be customers who are genuinely in the "wrong", meaning they are trying to scam or take advantage of a seller (although professionally speaking, most of what salespeople complain about is usually their own fault for not incorporating properly into their overall approach, and the rest is their responsibility to deal with in a professional manner - besides, the reverse is always more common universally), but the professionally competent salesperson (or in this case, the polite and sincere seller) will always do their best to treat all customers with a high degree of consistency and patience, if they want to be successful. Selling should never be taken personally - you will fail miserably, because no one trusts a salesperson, and no one wants to be sold by someone they don't trust. When I respond to an ad and receive no answer, or an uninformative answer, I don't take that personally either; I simply know that I'm dealing with a poor seller, and stay away. When I place an ad, I consider it to be my responsibility to answer all the responses it generates without exception, because that is what is required for me to be a good and trustworthy - and therefore successful - seller. The nature of the potential buyer's questions, or their possible lack of further response once answered, is just the way that things are; I can't control it, I can't change it (and since they don't know me, I certainly can't be insulted by it) - I can only control my own behavior, and I will not deviate from my own correct course of action just because someone else acts differently, for only my own actions are reflective of me.
By and large, I have found the sense of community among the folks I've interacted with on A'gon to be satisfactorily high as a group, and suspect that the ones who fall below the standard set by most tend to wander away after a while anyhow. Regardless, I don't feel that I have anything to complain about here in general - I enjoy myself on A'gon a lot more than I don't, and the site's helped me out with my audio goals a lot more than it hasn't. It's no great disappointment to me if not everyone who comes around here acts perfectly, or that I can't totally let my guard down, because I can't and don't expect those things to begin with. After all, as much as we audiophiles may be trying to escape it, this is still the real world. Happy listening in it!