Hmm... I thought everything in the 'comparisons' charts counted at least somewhat towards score. I'll have to test whether units count towards score. If not, this is a major flaw.
I do know that mothballed ships don't count towards score, stored resources do not count towards score, and
resources acquired by remote mining don't count towards score.
Now combine those facts with the units effect (if true) and you can see that it is possible to be vastly more powerful than your score would make it seem. Instead of colonizing resource rich mineral planets, built remote mining bases over them. Especially if they are small or tiny. You'll actually get more out of them than if you colonized!
Stockpile units and immediately mothball built ships for a while. You will have to spend some resources on refitting them to keep them up to date, of course, but you save at least as much on the maint as you spend on the upgrades. If/when you are attacked or need to attack someone else you just unmothball enough ships to do the job (including transports/carriers to haul all those units) and bury the poor sap who got in your way...
Reducing your
own score is easy. Mothball ships. Reducing someone else's score requires... compelled retirement of ships. (See above technique...
)
BTW, for all of these reasons I recommend NOT using score victory conditions.