Try Balistol, its a very good allround general purpose fluid, for anything. Have a nose on't web and get some. It smells a bit when first used, but it soon wears off.
It probably depends what you've got on them. I did a job in a factory where they used 'Sika-wipes' which I suspect would remove feces from a carpet. Otherwise acetone, which you can get from all good chemists and some bad ones. It comes in 50ml bottles for about a quid.
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