I don't think you will get many dealers stripping stock (in stock rather than OE stock) before they its sold. It's cheaper for them to take the chance and hand the bike over and hope it never comes back or runs out of warranty than it is to rebuild it in the first place.
Most are sold with just 3 months warranty anyway and the limited mileage the bikes tend to do means that by the time any problem raise their heads the warranty has passed.
£6500 is a lot of money to be spending on any second hand bike but there is never going to be a super fire way to tell if its as it seems. Even the most loved low mileage bikes can of been at the hands of less than sympathetic mechanics.
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If I have to take the carbs off once more...