A good micro worker site? None exist as each and every site that has potential is ruined by the idiots running it. The best kind of sites are the ones that have a multitude of buyers, in which you need to compete with a large scam artist community already milking these sites. I left eLance aka UpWork when their animation section was hit by "indian" scammers. They would come in with low ball bids, trick people into this long winded speech about how quality is now cheap, and then run away with the money. That market died off and I left. Now I pull in side animation with my own methods (some of which are shared on here, some you need to just think up yourself).
If you really want beer money you can scrape results related to your keywords daily, bot post a counter offer to the target client, present your portfolio for them to judge, and wait for a response for the rest of your sales hook. I also would never accept payments via PayPal unless they are trusted. My final note of advice would be to do something you know will make money. I know that animation still makes money, just not easy money unless you are shrewd like me. I have everything setup a head of time so it cuts down on work labor hours. My rates have stayed about the same so I actually am making more money now with less work than before. To get to here I had to spend a good chunk of setup time to make it work.
TLDR: There are no good beer money sites, you'd need to do everything on your own, and a good setup will pay off later in the long run.