I don't know if anyone here has a dream of traditionally publishing, but a very successful author I know made up a list of things to watch out for in a contract with a traditional publisher:
The big contract things for me are:
1. Length of copyright terms - which are ridiculous. Foreign and audio terms are for a certain number of years, the big-five contract should be to. Let them have the rights for 7 years and then they have to renegotiate or revert.
2. Non competes - I could spend a whole day talking on this subject.
3. Out-of-print clauses - does an ebook constitute "in print" ? Can they use print-on-demand? - For me it's no in both those cases. Ridiculously low thresholds to determine a book is "in print"
4. Taking too many rights and not reverting them if not exercised. If you take my graphic novel right then you better produce a product (or sub-license the right) within 2 years - if you don't, then give it back to me.
5. Sneaky things like adding within an indemfication clause that the author's next book will be that book - which if they take up to 2 years to produce means no new books by the author for 2 years!!
6. Royalty rates that change for "deep discounts" where the publisher actually makes more if they give the bookseller a deep discount because a 1% change the author from making 15% of list to 10% of net. So the bookseller makes more the publisher makes more but the author makes less.