Any best tips or products to clean a grubby fabric sofa?

[Ludlow2]

I.am helping someone who has moved into a rental and the sofa needs a good clean. We have tried but to no avail?
Any tips.

Rent one of those karcher/vax things which come with upholstery attachments

But for the long term I never buy sofas or chairs which dont have removable covers, I like to chuck them in the wash quite regularly, they get a bit stale even if they're not actually dirty

Dr Beckmann but test for colour fastness first. Any removable covers stick in the washing machine. I’ve never had an issue with this even when they say dry clean only.

Dr Beckmans is great for any tough stains I mix ace stain remover (green bottle not the white one) with comfort/lenor and scrub that usually does the trick
Is there any way at all of washing them in the machine?

Covers not removable. It is the arm rests mainly. May buy some covers for them if not improved.

Definitely try a wet upholstery vacuum. I just bought a small one as my sofa had pee stains from toddler and it cleaned them up easily. I'm sure you can rent or borrow something similar for a single use.

Shaving foam for arm rests.

Last week I used vanish upholstery spray on the arms of mine. I scrubbed with a stiff brush and then rescrubbed twice with clean water. Worked well but not perfectly. My sofa is a light beige, not sure I'd do it on a darker one.