Regarding that one, I don't like the fact that Omegastarscream was dealing in accounts, but I do take other factors into account before leaving someone a neg for account trading--and one of the main factors is other positive feedback. Who left it and when are also important. OSS had pretty much proven himself to not be a scammer by the time I visited that thread, so I did not think it was appropriate to leave him a neg. The other users didn't have those reinforcing positive feedbacks, so all I had to go by with them is the fact that they were looking to buy/sell an account.
This type of activity is either an indication that someone is a scammer, or it isn't. There really is not a lot of gritty area here.
Your response about being selective about who you Red Tag for dealing in forum accounts makes it sound like you don't want to debate your trust ratings on their merits, and avoid doing so by avoiding Red Tagging anyone who has a decent chance of having supporters, or anyone who has a decent chance of making a coherent argument against your Red Tag. Lets be honest, most of those that you Red Tag, especially those that you Red Tag for this reason have no one supporting them, and can probably not speak english well enough to make a coherent argument to support the Red Tag is inappropriate.
You should be willing to defend every one of the ratings you leave, because every rating you leave has the backing of your reputation. If the exact same concerns come up multiple times, you can point to a previous discussion if you wish. Ignoring concerns is not okay.
There are going to be inconsistencies, I don't know what to tell you. Point them out to me and eventually I'll correct them or otherwise respond to the accusations.
OSS is not the only person that avoided a Red Tag in that thread, and he is not the only person you skipped over (in chronological order) that posted in that thread. There were others that did not appear to have any meaningful reputation at the time.
Since you solicited the question, why have you not left Lauda, mexxer-2, or yahoo62278 a Red Tag? They all engaged in similar business activity that you are very actively Red Tagging for today, and in the case of one of them, made a post asking about the price for 10 forum accounts, which if you believe to be a serious request, would make him a very serious/major account dealer/farmer. I don't know if you have heard the expression "going after the big fish", but this means you want to go after the most serious offenders, and someone who is buying up 10 forum accounts at a time is someone who fits this description.