it depends. it could greatly improve an average woman's looks. but i've also seen instances of it hurting the appearance of an already attractive women.
if a woman has been otherwise been confident in her whole life and has good inner game, if you will, but has had social anxiety due to a large nose i think plastic surgery would be great. i personally don't like noses that are so perfect you know it must be plastic surgery, but trimming a large nose down is fine.
i think the larger issue with me revolving plastic surgery, is that in most cases it is an attempt to fix what is wrong on the inside. therefore, i would view it as a red flag. especially if the girl is already very attractive. so many 8+ girls want plastic surgery and i find that to be a turnoff. but if it's just meant to correct the appearance of an otherwise healthy person, sure it's fine.
i don't know if this is the best place to get advice on men. pickup forums have a lot of guys that don't have any success with women, many of whom should. also you'll find a lot of misogynistic men with sociopathic tendencies. it's a fairly mixed bag. there's also some great guys who are trying to better themselves, but it's hard to tell the difference really. personally i'm trying to detach from my sociopathic tendencies, as they've creating a lot of negativity in my life. i'm not a sociopath so learning some sociopathic behaviors was damaging to me. but i digress, you will find people in pickup to be far more superficial than men in real life. i think that's one thing that rings true for most guys around here whether they'd like to admit it or not.