Somewriter, the most important thing is transparency. You, as a writer, should have all the relevant information on the website you are working for:
1) what are its client-end sites?
2) where is the site/company/owner(s) located? It does not matter if they are located on Mars or Jupiter as long as they are honest about it.
3) is the site owned by a company? It should be.
4) management, owner, admin contact info? Do you have it and are you able to reach them when you need to?
Legits do not hide pertinent info from customers/writers and they certainly do not use pseudonyms and fake names when dealing with either.
You need to know who's accountable.
Another good indicator is their recruitment policy. Did they vet you before signing you on? Did they ask for proof of your academic qualifications, etc.? If they care about their customers and reputation, they would.
Fines: stay far, far away from companies/sites which have a fine policy in place.