FL170 and Cleared to Reenter - We do allow for nav tolerances, so clipping a corner by a mile or 2 is usually just monitored, not "tracked down" so to speak, although we will broadcast on any relevant frequencies. Occasionally you do get someone who is very, very lost (once had a PA28 who landed at TVL without a single contact with any control agency .... he was aiming for the GAAP at Ayr! Had another guy who actually did call for a clearance, giving his position as 10nm sth of TWB, problem was, he was actually 10nm sth of AMB and had been in CTA for the previous 15nm)
In the latter case, he was trying to do the right thing, was just very lost. We helped him find some easy to spot landmarks from his VTC so he could re-orient and organised further assistance from Brisbane radar to keep him clear of BN CTA on his way to MC, as he was unfamiliar and a little shaken. He called us after landing at MC to say thanks and to apologise and we had a great chat about the local airspace and procedures. Paperwork was still filed, but we annotated that we had had an in depth debrief with the pilot. I don't know what CASA's actions were following that. But I was satisfied with his attitude and the fact that it was a genuine mistake that he would be determined to avoid making again!
As far as grumpy controllers.... yes, there are some. But most of us are very aware of the danger of "intimidating" a lost and possibly distressed pilot. No matter how pi$$ed off I am (and regardless of what I might say to my peers off mike) on the radio, I stay calm and try to help if necessary, once the acft is safely on the ground, that's when we usually get the message passed that they need to give us a call, no need to add another worry while they're trying to fly.
But to answer your questions, any VCA is a reportable occurence (for statistical reasons even if no other action is taken) and, personally, I would much prefer you to 'fess up and advise your intentions, rather than just slink away. A clearance through may very well be available to you, so you might as well get one
, especially if you are landing nearby and we will be able to "track you down" easily anyway! And more seriously, if your inadvertent VCA has created a conflict, knowing that you are on frequency makes it easier to resolve through mutual traffic, avoidance instructions etc.
Thanks for asking!