Your firmware probably doesn’t have a write strategy for your discs as they are newer 16x discs. It has nothing to do with the drive knowing they are ‘crap’ , it likely reverts back to 4x for being an unrecognized media code. BTW, you never posted if they are +R or -R, nor the media code, which is the only thing of relevance. Memorex distributes discs from all sorts of manufacturers of media, they don’t actually make their media. It’s entirely possible that they are good discs and your drive doesn’t have any firmware support for the discs. Burning 16x discs at 4x, without a proper write strategy no less, will probably result in average burns at best.