The VAT number is unlikely to be dodgy as eBay are obliged to verify that is correct. You can do this yourself via HMRC's website.
The address details shown will depend upon where the items are located. If the seller is shipping items via a UK fulfilment house the address and VAT number should be those of the fulfilment house. If they're not using a fulfilment house - i.e. the items are not located in the UK - the address will be either the seller's own Chinese address or that of the Aberdeen HMRC office as they handle VAT registrations for non-established taxable persons.
Give me ambiguity or give me something else.