On a site I manage we have a view of recently updated products. The problem is that once a user purchases a product, that product is updated, which shoots it to the top of the list.
As far as I can tell there's no reason for a node update to be triggered simply because the product was purchased.
My first thought was the stock. However, uc_stock is directly calling db_query on uc_product_stock table and not touching node, or is it doing a node_load/node_save.
The closest I've found is that the update is triggering the nodeapi hook with the 'update' op. nodewords is picking it up as an update operation and I can see it in the dblog.