How do you manage "Scope Creep" when it’s disguised as "small, quick favors"?

[Btaliat]

That's where professionalism comes into play. Most clients always want the freelancers to do the scope creep with the notion that it is just a small favour. The freelancers have to make it clear that there will be payment for any extra things that he's doing. It is left for the clients to agree to this or not agree. Freelancers should have a solid contract to be signed to back this up. What do you think about this?