My advice:
When you see an informative posts (not just random bull*hit or spam) and you have got some merit's to spend, don't hesitate and do it. Just don't look at the account rank/nickname or anything else.
That is the ideal case scenario but that is not going to happen in my opinion. This is because majority of people act based on emotions instead of logic. But this problem is limited only to merits given by members here. I do not think that merit sources are also doing this. Also, some of the senior members did gave merits to new members (in fact some organised exclusive giveaways for low ranked members). So we cannot make a general opinion.
Also, I see admin is helpless in this case, he can only request members to use their merits wisely.