I was just about to post exactly the same answer to the one above. If you dont have any paint or you dont want to buy a whole new can, you could maybe get one of them small "tester" pots for next to nothing..
I sympathise Supernick, I'm in the same position but the marks are hair dye (girlfriend stupidly asked me to apply the colour to her hair and I did not realise the top was cut off when I shook it !).
Unfortunately, washing the wall even straight away has just taken the paint off and the colour of the wall is the most obscure sort of magnolia I have ever seen.
Countless trips to the DIY store coming back with handfulls of testers later and the nearest I can find to it is Orchid White. It still means I have to paint the whole of one wall though and hope they dont notice its not a perfect match to the other 3 walls !
Sugarsoap is probably the best bet, get it from any DIY shop. Just dont get the wall too wet. Sparingly wash on the sugar soap solution - gentle scrubbing is OK - then wipe off with a seperate freshly rinsed damp cloth.
If that doesn't work then you'll have to get the paint brushes out!
Hi there, you don't say what the scuff marks are caused by, in any case cheapest safe methods are toothpaste on a dry cloth or for extra abrasion, a bit of bicarbonate of soda mixed in.
if they are marks that might show through with only one coat of paint ,spot coat it first , or use a thin coat of gloss on the marked area then paint it.