How do the rest of you clean fabric couch?

Check the tag under the cushions first. W means water-based cleaner is fine, S means solvent only, WS either, and X means hoover only. Water on an S fabric is the classic way to end up with rings, which sounds like it might be what happened. For a W couch: hoover, then a little dish soap in warm water on a cloth, dab and blot rather than rub, work from the outside in, and dry it quickly with a fan. If you've got a water mark, dampen the whole cushion panel evenly and let it dry in one go - the ring is just the edge of a wet patch.