The wiki and forums generally seem to say that Cheese Tray quality acts the same as (for example) barrel quality for grape juice/wine. I routinely get q66 and 67 curds from my Curdling tubs and put them in Q100+ trays. The resultant cheeses never seem to be higher Q than the curds that went into the trays.
Now this was passing observation. I'm planning on actively logging my cheese now to see what happens and coming up with a few variable quality trays.
Has anyone noticed the same, or recorded cheese trays specifically *increasing* the Q of cheese?