My Charlie was clipped before I got him. They never even asked. When I called the store, they said the breeder does this before turning them over to the store to be showcased before being sold. When I took Charlie to the vet, Dr. Lawrence said they "shredded" his wing feathers and that they cut way too many feathers. They should only cut 3-4 flight feathers above the vein line. She doesn't even like to do it unless it is for the safety of the bird. Sola, who is the most skittish bird was going to her's clipped and as we took her out of her cage (she had a raspberry on her head like a helmet) the doctor freaked because it looked like Sola had some type of head trauma. Sola didn't react normally I think because of that. Once they took that helmet off though, she flew around and around the room. Dr. Lawrence said, now how would you feel if that's something you could do and then all of a sudden someone took away that ability? I left without clipping sola (I wanted her clipped because I was afraid of her running into windows and walls) and I'm sure glad I did!
I was warned sometimes but not always, cutting their flight feathers for our convenience causes insecurities in the birds as they are prey animals and we've just disabled one of their biggest defenses. I agree. If I felt like I was being attacked and was running in knew deep mud instead of being able to run free, I'd feel less than too. I'd have fears and nightmares.
Sorry for being so long winded. Not clipping, unless for medical reasons or severe safety issues, no clipping is my motto.