The arms of my sofa are filthy

[PinkOboe]

I don't normaly sit on this one, it's where the scummy kids hang out

I don't have one of those floor cleaners with an upholstery nozzle. I do have a steam cleaner

Is there a good way to clean them that I don't know about?

Yes - warm water with stardrops and a clean colourfast cloth. Wring the cloth out well so it's just damp with the soapy solution and rub over the dirty sofa arms in a circular motion. I cleaned a very grubby sofa like this with relatively little effort.

Thank you! Are star drops to be found in the supermarket?

1001 carpet cleaner works well

Yes - don't get the one with ammonia though, you just want the basic one. Places like B&M and Home Bargains also sell Stardrops. It's cheap. I've also scrubbed a carpet clean using it - it was in the small kitchen of a rented flat.