As a Board Certified Plastic Surgeon in his 22nd year of private practice, I have seen many people who have had prior cosmetic procedures done by other doctors. I am often asked my opinion of the work. I try to avoid this answer at all costs.
One rule I have is to never ask who performed the surgery, as I do not want anything to bias my opinion in either direction. My personal feelings toward a particular doctor, or my prior experience with patients of his/hers, should be left out of the equation.
I also state that it is impossible to judge a result without first seeing the before photos from the surgeon (no offense, but some patients use a before photo that was altered or from many years in the past that do not reflect the true appearance on the day of the surgery). A slightly wider or larger breast on one side may be a horrible error, or a miracle of surgical wizardry to even approach two even sides.
With regard to scar quality, unless it is horribly malpositioned, often the scar depends mainly on the genetics and skin of the patient and the care given after the procedure. An ugly scar does not mean your surgeon did a bad job. When I revise scars, I even tell patients that there is no guarantee it won’t look worse.
I advise patients to look forward, not back. You cannot change the surgery you had, but can try to achieve a better result in the future. I am always happy to have an honest discussion of the options for improving prior surgery, but you need to let go of anger and be positive for a healthy start on getting better.