I think this mostly succeeds when dev don't "need" the cash. 

Unfortunately I have seen plenty of brilliant minds letting foss projects go while life and corporate work (getting paid always wins). I really thing the economy as a late has exacerbated this. The Awesome Lists  follow are mostly abandon-ware. Like really abandoned. I have taken time to make PRs in the past to prune these projects, it can take all night, then the maintainers never merge. 

It takes real discipline to accept donations, maintain convictions when you also need the money. Thomas Sowell also spends a great deal of time on human psychology of incentives.