I could see decaying airdropped merit, though I'm not convinced of it currently. If it was done, it may be best to do something like this:
- Your current activity score as of is recorded, which I'll call EPOCH_ACTIVITY.
- Your merit score is defined as max(0, AIRDROPPED_MERIT-(CURRENT_ACTIVITY-EPOCH_ACTIVITY)/7) + EARNED_MERIT.
If I'm reading the formula correctly, active users would lose 1 airdropped merit per week (actually, they'd lose 2 airdropped merits with every activity increase, which is on a biweekly basis.) If it's something that is important to you and the community, that seems like a fair way of implementing it.
Those who are active and contributing to the forum shouldn't have trouble keeping their merit score up, and those who are here to shill and spam will be able to see themselves being slowly demoted. An airdropped Legendary who earns no merit will be demoted to a newbie in a little over 19 years. If you can't learn to earn merit in 19 years, I guess you should be demoted to a newbie.
I like that the formula doesn't affect inactive users. It does seem like a very fair compromise.
You can be an active member of the forum posting constructive replies and be engaged in active discussion and still not be merited. This is what I don't get about the merit system. People tend to merit popular users that post threads and not users that post constructive replies because constructive replies seems to be the norm for many users. So essentially, you only get merited for going above and beyond which doesn't make any sense if you're going to introduce merit decay. Secondly, it would act as a disincentive to give merit away knowing that it's just going to decay way making your overall merit lower.