So this is the "trial-by-fire" approach. I inadvertently use it a lot as well. I'm trying to soften the approach however.
However, you can also wrap that in a friendly approach as youlost_thegame mentions - simply acknowledge the potential of the idea first (ie, positive energy) then go in with the tough questions.
I find even with friends and close colleagues, if I stick to the "nice first, then difficult questions combined with enthusiasm", I can often critique the idea while making the entire conversation positive. Often the faulty idea gets discarded by it's owner after consideration.
However, you can also wrap that in a friendly approach as youlost_thegame mentions - simply acknowledge the potential of the idea first (ie, positive energy) then go in with the tough questions.
I find even with friends and close colleagues, if I stick to the "nice first, then difficult questions combined with enthusiasm", I can often critique the idea while making the entire conversation positive. Often the faulty idea gets discarded by it's owner after consideration.