What do people in Singapore think of other Singaporeans who go under the knife to get a better look or body?

They think that it is just all part of nature.

Singaporeans wouldn't normally think twice about undergoing cosmetic surgery to refine their looks. Even if they know that it is fake/unreal and the like, they still go for it.

Why?

Simply because today's society is very much based on appearances. Appearances mean almost everything in today's society.

If someone wants to get a job and the person is fighting with someone who is 'uglier' than him/her but has slightly better qualifications, the correct decision to be made by the boss would be to choose the one with higher qualifications that can bring up the company's worth. However, the boss would think that the one that looks nicer would be able to carry out his/her duties more efficiently.
Another problem is the over-exaggeration of the term 'personal grooming'. The term has been coined and brought to a much newer level in Singaporean society. In fact, during job interviews it is important to keep track of your personal grooming and show the interviewer that as interviewee, you are an aspiring one that is capable of the job.
However, to do this, you must first look good to create better first impressions. Sometimes, the interviewers just look out for the appearances and look at nothing beneath the skin. Especially not qualifications.

So what are the use of qualifications and studying hard if today's society looks out more for appearances/ first impressions than to actually assess a person properly and look at a person holistically.

Back to the main point.

An "Ugly Singaporean" would possess certain traits that makes him/her, well, ugly. The problem is, the traits might not be very accurate in discerning a person's 'ugliness'. As I wrote in the above, Singaporeans nowadays have their sights set on people not with qualifications but, more of people who make a good first impression through their appearances.

Then there is another type of ugliness which I regard as the type of ugliness Singaporeans, and the entire world while you're at it, should be based/assessed on. It is the ugliness of...
Humans. All humans. The deep, dark ugliness.

1) Hypocrites.

Well, actually that pretty much describes the world.
Everybody is a hypocrite. Aren't we?

The 'ugliness' of an "Ugly Singaporean" shoudl never be used to assess people. In fact if you asked me, a lot of people are seriously too jugdmental.