I don't know how old you are Barry, but I'm very old :D and remember quite vividly when a Pediatrican/Psychologist named Dr. Spock came up with a "purely positive" method of child rearing.
This method advocated "time outs" and reasoning....with a toddler...
for inappropriate behavior... marking only the "good" behavior with lavish praise and ignoring "inappropriate" behavior with either NOTHING or "reasoning" or time outs.
No negative reinforcements other than "ignoring".
Produced a generation of BRATS who rarely see consequences for inappropriate behavior.
At some point.....corrections; (ie a negative stimuli) be it verbal, physical or a combination of BOTH really does have its place in training.
We see the results of "permissiveness" and overlooking the behaviors of dogs (I call it making excuses for the behavior...but you can call it whatever you'd like ;) ) and it truly is a result of the same type of mentality Dr. Spock used. (By the way...were you aware that Dr. Spock WAS NOT A PARENT??? No kids. Zero.)
S C H U T Z H U N D (I spelled it slowly...lol) imprinting differs very little from the pet in that our dogs are expected to be tolerant of their surroundings......but I have to tell you......we accomplish this without strangers tossing food at them!
You corrected yourself; which is good......because the HANDLER does indeed have the task of reinforcing the positive and reinforcing via correction what is negative.
Time outs.....and the Spock mentality will be as ineffective on this generation of K9's as it was on the generation of "selfish" kids that were raised using it.
It really IS OK to reinforce poor behavior with a correction.....you won't go to hell for it; and your doggie won't be "angry" with you.......and gee......he might actually be conditioned to NOT REPEAT THE BEHAVIOR if you're consistant enough with the imprinting! What a concept huh.