Someone had the right idea in this forum last year but just hadn't (yet?) figured out that there's a quicker and simpler way to do it. You just have to think about it a bit. No blatting required*.
* Is that really a verb?
I'm intrigued to know more... happy to talk via pm if needed. I know of only two real mission types that are reliably fail-able. There's a few others i think will fail only if your ship explodes (courier missions, for example)... But a good deal of missions are only able to be softlocked, not failed (that is, put in an uncompletable state).
To be specific on these as there isn't much point trying to hide ineffective tactics.
- assassinations can be failed if the target is destroyed by police without your intervention
- salvage and hijack can be softlocked by getting the cargo and then destroying it, or destroying the target in the case of hijacks.
- deliveries can be softlocked by destroying all the cargo
- Couriers i think can be failed by blatting yourself
Most other missions e.g massacre, surface scan, powerplant destruction, source, donate, mining, can't be deliberately failed except for having the timer expire (and abandoning them won't work).
There's one large category I've deliberately omitted, and another minor category, which are deliberately fail-able without needing to die.