A correspondent writes to say that she has found such sentences as these on the internet:
Keeping these things in mind, you can look well in black dresses.
Peasant tops look well on small busted girls.
She goes on: 'I was always taught that to look good is to be attractive, while to look well is to appear healthy. According to that rule, this use of well would be incorrect. Is there any time when this use of well is acceptable? Is it a regional usage?'
The examples - and there are indeed quite a few of them - suggest that this is an area where usage is changing. I share my correspondent's intuitive preference for good (or great, smart, etc.), and so do three female informants (in their 30s, 50s, and 80s) who happened to be in my house when the email came in. The interesting question is why the change is happening.
I think that well is shifting because of a change in the usage of good. In the early 20th century, look good and listen good emerged in American English in the sense of 'look/sound promising'. The OED has a first recorded usage of 1914. This developed into a general sense of good to mean 'in a satisfactory frame of mind', 'coping well with life', and suchlike. It's most often heard these days in response to a How are you? type of question. I'm well means 'well in health'. I'm good means something like 'things are OK right now'. It's a new semantic distinction in English.
However, it's colloquial, youthful, and originally American, so many older people, especially in Britain, don't like it. (Ironically, pedants who are the first to complain when a semantic distinction is lost - such as the distinction between uninterested and disinterested - are the first to complain when a fresh semantic distinction appears in the language.) And because good has taken on this colloquial resonance when used adverbially, it has made some people sensitive about its use. They may even sense a parallel with such criticized expressions as go slow, where more formal usage requires go slowly. So they look for a more formal alternative expression, and find well available and already being used in a general sense of 'successful'. Indeed, locutions such as go well and do well date from Anglo-Saxon times, actually predating the 'sound in health' sense by a few centuries. So I don't find it at all surprising that people are beginning to say and write It looks well on you, and so on, and would expect it to become more common as time goes by.