I have between 100 to 300 auctions a day on average I think.
But on the other hand I always have that many stuff, and lots of different stuff too (greens, blues, epics, trade items, cloths, etc etc.)
My auctions are spread on alot of things (so not 100 stacks of ores, but lots of different items in different trades).
I've had a few questions from other players, but generally they leave me be.
Most of the time I say this is the banking toon for a few guilds, and I maintain the GB
I also buy quite a few items to sell em more expensive again. Probably that also helps in not drawing alot of blizz attention (if any).
It's not only sells but also buys (and sell again ofc).