An accidental spillage of paint or any other substance is normally covered under most homeowner policies when the spill damages the dwelling. This is a fortuitous event and not specifically excluded under most policies. If by 'rug' you mean a true rug and not wall to wall carpeting then most policies would not cover such an occurance as most policies are named peril for personal property including rugs. I've handled claims in many states and can't recall a policy that specifically states spillage of paint as a covered peril. As for the cleaning, as a former Insurance adjustor unless the cleaning is performed immediately and by a professional using a truck mounted extractor the paint would not be totally removed.
Now it is true that your deductible would apply in this instance but there would also be a percentage of depreciation applied to your loss and in most cases the depreciation is not refundable even with the 'Replacement cost endorsement'.