RE:Testing methods They are being honest up front. The first batch of 30 did not meet expectations. They are now trying to find the problem(s). Ideally, you want all of the data points along the line. You want the different methods yielding the same results.
The core is split in half or in some cases sawn in half. There can be a tendancy to send the better looking half in for assay. Doing so is discouraged but there are very junior employees doing the work.
There is no implication of salting.