Yeah, you can always tell when an engineer has little or no manufacturing experience. There can be countless phone calls and emails back and forth, telling them they need change something. It either cant be machined, or the cost to make it by their design would be astronomical. More times than not, you loose money just from the time invested with collaboration. After a while, you can just look at a print, or model and tell where it came from, and instantly factor in "X" amount of hours to add in to the quote for ignorance.