IMO: What The HO Is And Isn't.
For myself, a HO is only an HO (as usually complained about) when there has NOT been a any type of sharp turn or maneuver by the opposing pilot for at least 3-4 seconds or more prior to the moment of the HO, i.e. we are relatively alone 1 v. 1 and he planned, presented and pursued the HO situation deliberately. HO angles can occur during furballs and are most often unintentional, and sometimes the best option of the moment. This is not really the classic HO of whiner fame.
Having said that, I believe any possible angle of a shot at me, at any time, at any place, from any opponent is still a "fair" shot. It may seem cheap at the time, but
(a) he took the opportunity (however, dweebish and stupid it may be) and made the hit, and
(b) I wasn't good enough, smart enough, or paying enough attention to avoid the shot. PERIOD My bad. I "let" him get a shot on me.
The HO is a 50-50% proposition so it's actually the "fairest" engagement a bandit can give you, and therefore, one you want to avoid.
Result: he got an essentially skill-less kill and gained no additional ACM skill or practise, and has actually reinforced this condition in his flying. I got a sharp reminder to play the game my way, not his.
But this outcome doesn't happen very often any more because now I take my plane Out Of Plane with him just prior to the moment I expect him to shoot, usually with a rollover and pull up for a vertical Lead Turn. Done properly, only the luckiest of shot will will even ping me. While he's pushing his nose down or around to follow me (losing E or turn advantage) I'm already a half-step ahead of him in my OODA Loop process and resulting manuevers, i.e. I've gained at least some angle and working one step ahead of him on getting a kill from his 6 o'clock.
Result: I have fewer deaths AND more kills in this situation than before as I've converted an originally 50-50% engagement into something more in my favor, like 80-20%. Effectively, my kill-to-death ratio went up as did fighter score.