Good for you, actually reading the contract before signing it! You're right - in general, if it looks too good to be true, it probably is.

Do you subscribe to the For Author's Newsletter here on Writing.com? I'm one of the editors, and this question has come up several times in the last month, prompting me to rerun an earlier column I wrote for the Action/Adventure Newsletter ("August 30, 2004" ). It's in this week's issue of For Authors (along with an in-depth discussion of the differences and usage of hyphens, en dashes, and em dashes).

I won't comment on CLA, since I have no personal experience with them and what I've read on the Internet isn't what I'd call "conclusive evidence" that they're not all they appear to be. But in general, remember: agents work for you. They get paid when you get paid. If they are in any way affiliated with an editing service, book doctor, etc. that charges you a fee - be very wary. 15% of royalties is customary, and you may be asked to cover reasonable expenses of marketing your book (postage, phone calls, etc.). Anything beyond that should set off warning bells in your head and make you think twice.