Own goal - accidental or deliberate?

[Ian]

re rules 25.2.2 & 25.2.3 - field goal in own basket.
accidental vs deliberate and how to define.
I've now seen three situations of interest.
1 - under 11 girls, fair standard, end ball passed in to defender who had a mental block, shoots, goal. Credited as accidental (in this case a refereeing supervisor happened to be ref'ing and did know the rule but felt that it was accidental).
2 - under 18 boys, top standard, similar but defensive rebounder got possession and put it straight back in (mental block again). In this case, credited as goal and refs didn't even know there was a relevant rule.
3 - under 18 boys, ok standard but not main competition. Both teams trying to lose grading game to stay down a level. I didn't see this one but was told about it. For the last ten minutes of the game, they simply attacked their own baskets and defended opposition basket, trying to beat themselves. Refs didn't know rule and simply kept scoring.
I thought that the rule was probably meant to cover accidental tip-ins from (say) a rebounding contest and that a purposeful shot taken at the wrong basket was still deliberate even though there is obviously no intent to score for the opposition.
Anybody know whether there is a definitive interpretation of accidental / deliberate?
Thanks in anticipation, hope it's of interest. (Only time in many years of following basketball that I'd heard of the deliberate attempt to lose - surely that's not why the rule was created?)