These leagues are infested with draft junkies. They enter 40-50 drafts, for the "Action". They only plan on actually running 3-4 teams they like the most. The rest they abandon. It ruins the integrity of leagues. Don't kid yourself, the leagues really end up disasters. I'm talking 95% of them end up this way.
They are some good commissioners running decent private leagues. They stay on top of things. If someone abandons their team, they have someone to step in and takeover, make sure the team isn't participating with 8 guys on the DL. The leagues have structures.
A lot of the leagues are keepers. These types of leagues promote perpetual involvement as they exist year to year. Yes, most involve a fee. Yes, that can be risky. But, most are not scams. The fees are there because we all like to gamble a little and money keeps it interesting. Reward for hard work. Face it, you spend $40 to take a date to a lousy movie. The same money can get you a place in a league where you can participate an entire season and perhaps reap rewards at the end of the year.
PUBLIC LEAGUES WILL WASTE YOUR TIME. I HAVE BEEN IN THEM FOR YEARS and only once did the entire league stay till the end.
I have spots in 3 different leagues I am running. 2 Auction Keepers, One Standard live draft keeper. The fees range from $20-$50. I return 100% in prizes. I collect through PayPal as they can provide recourse should you feel there is impropriety.
They also many other $$ leagues on the message boards. Give them a chance. Even if you don't get paid, as long as the league remains competitive, you get a lot more for your money than a lousy movies. SEARCH THE MESSAGE BOARDS.
If interested in my leagues, write me at firstname.lastname@example.org.
I'll answer your your questions as best I can. I'll be honest and run good leagues.