Ive seen loads of people send them money, if you look on steemd it looks like you got 50 or more votes but you got as you say f-all, dont use them again, there are good bots that help, randowhale and minnowbooster are the best and bellyrub and koha are good voting bots. When you make your next post send $3 to minnowbooster, you nearly have $3 and you will get a very nice up vote, or if randowhale is awake you send him $1, i just stick to those 2, or you could convert your dollars to steem and power up a little