It's pretty obvious that there's "always" a chance. I mean, seriously, is that how members are suggested to answer eachother on this forum? I hope not.
Basically, you know what he was saying and as do the rest of us. Here's a better answer, though, (sorry If I'm coming off as an ass but I mean..c'mon what you said to him just had me go "hurr durr no shit" :/ )
Yes there's a
chance that you'll get caught, but because these macros are being built more and more with "random" and "rounded random" etc coords and sleep intervals, it's becoming harder for them to track basic patterns. My advice, though, is stay away from the AH bots unless you have a bot that can do other things, like Hero switch, resume game, and exit back to the character screen and re-begin the AH, every random few minutes or so. That would work at throwing off Bnet and make them think you're actually logged in, doing your thing as a human being.
That being said, I'd like to mention the obvious and already well-known, Warden. We are (I hope) all aware of the fact that Warden is already inside Diablo 3 and it's only a matter of time before they find a way to screenshot or code watch or etc that they do with WoW. So you should personalize scripts, programs, etc as much as you can (personalizing a program is to find the source code, and recompile the script yourself with different function names, handlers, and etc. A good example is to google making an undetectable Cheat Engine, as that program has been personalized by many a hundred or even thousand times over).
Furthermore, I'd like to mention that as long as there are actions being taken to secure and prevent, there will be those with the persistence, knowledge and the ability to bypass or work through or alongside the security measurements in order to continue to gain the upper-hand in a world Far beyond what the average 'gamer' sees.