> can't change a single line of code in the product without breaking 1000s of existing tests

> all held together with thousands of flags

> ridden with mysterious macros that one cannot decipher

> needs to understand the values and the effects of 20 different flag

> Sometimes 100s

> only reason why this product is still surviving and still works is due to literally millions of tests

> The fact that this product even works is nothing short of a miracle!

Sorry, but I can't think of any adjective for this mess other than just "bad". That's some truly industrial grade slop, and I hope whoever worked on that got paid handsomely for it.