Hitching in Morocco is good despite the scarcity of vehicles on some routes. Bring a big bottle of water, a hat, and maybe a book to read. Many people will not want payment, but it can be hard to avoid the interest of grand taxis (who will definitely want payment). Sticking out the index finger instead of the thumb is the local way apparently.
Compared to the hassle of the cities, hitching in Morocco is a very pleasant experience and a good oppertunity to meet some genuine friendly people who don't want to sell you a carpet.