I promise I'm not a wrecker, I just have trouble finding Marxist sources for these things that aren't big books on top of what I'm already reading. I think I understand that it says the exchange value of a product is proportionate to the labor time used to create it. Am I getting that correct? More labor-intensive commodities, or products requiring more specialized tools to make would cost more. And I know I've heard the criticism before. Heard it pretty much all my life. "Is a cookie still worth its labor if it's burnt? Is a pie worth the labor if it's a shit pie?" I have heard people say that Marx addresses such criticisms in Capital, but I haven't gotten around to those tomes yet. Could someone explain to me how they are addressed and maybe straighten out other things I may have gotten wrong?
Exchange values are based on socially necessary labour time, not just any individuals labour time spent on making a commodity. In other words, the social average expected time taken to make any given good is what informs its exchange value. This means that exchange value is inclusive of the average number of burnt cookies produced by an average chef/cookie machine.
Machinery imparts no value into any single good because most machines can produce tens of thousands of commodities before requiring maintenance or replacing. The labour time spent making the machine is distributed evenly across the commodities it produces, so if it took 150 hours to make the machine, and the machine makes 50000 things before it breaks, each commodity has 150/50000 = 0.003 hours of labour time imparted as value into the object, I.e. it's basically a rounding error.