I have seen legendary members say that they have a hard time finding posts to merit. In my case it's the opposite, I have less merit than I would like to send. Sometime, seeing a post worthy of merit, I've thought: well, as soon as I get the next smerit, I'll come back to this post and give it a merit.
That exact same thing used to happen to me before I got tapped to be a merit source, and I was earning a pretty decent amount of merits back then, too. But once I (or anyone else) became a merit source, I had both my earned and source sMerits to use, and believe me you get plenty if you're a source.
I only get 100 source sMerit to give out each month, and I am often finding myself being out of source sMerit and earned sMerit. Over the months, I tend to give out a lot of merit at one point during the month, so I often have either no merit, or a lot of available sMerit to give out.