spiral45
1. Is there anything I can do to prevent having my trading pass disabled in the future?
4. Just out of curiosity, what is the quickest a trading pass has been restored? And what's the longest?
1. No, not really. I'm sorry. I mean, unless you want to be eccentric and perhaps PM a Mod/Omni or Admin every time you're considering buying something, excepting a trade from someone or receiving a gift from someone... in all likely hood, they probably can't tell you if that other person has a "tainted" item anyways; so the answer is still no.
4. The quickest I heard of (not sure if it was true) was a few minutes. Though if that one isn't true, than the next fastest would be 1-3 days.
The longest going one right now that I'm aware of... said they were either nearing 4 years (of trade-ban) or already there when their trading was finally restored.
However as the Mods and Omnis will tell you each case is different and the amount of time differs considering the severity of the case; the number of items and how many people got caught by it.
Quickest solved cases seem to be Glitches on the sites part (like: buying/selling item to a NPC for too much or too little, and other glitches).
However if you are guilty of something (like you for certain did something like... let's say "Gold Brought") you will be perma-banned within a month (from what I have seen).
These are all based off what I have seen and may hold little value toward helping you understand your case; nor may they be entirely accurate.