We give free samples to our customers. Currently Dear does not handle the proper GL cost account attribution for the items. The only way to do this is through manual journal entries which, if you do this a lot, isn't very efficient.
Although not optimal, one way to deal with this is to create separate SKUs for samples which have a BOM of the product for which it is a sample and sets the GL accounts as desired, for example setting the COGS account. The sample products can be auto-assembled when sold, or bulk assembled to have on-hand stock and put in a samples area of your warehouse.
I have also started this discussion in the "Tips & Tricks":