Most recommended places in China

The closest you're going to come is Hainan Island. Other than that, Yunnan and Guangxi get rather chilly in the winter and there's no heating or insolation. Guangdong is rather polluted. There aren't many expats in Guizhou or Jiangxi. And it snows in Zhejiang.

For sure. Hard to find a warm place other than Hainan...or perhaps Hong Kong Island?

The problem with China, as mentioned above, is most places from Shanghai south do not have heating...at least the older places.

Finding a place in China that is not polluted is going to be tough....and most travelers there who are working will be younger types. The pay is pretty low.

Have you been to China before?

"Lovely beaches" and "warm/hot all year around" are problematic. I agree that Hainan island comes closest to meeting those criteria.

As for the other criteria, Hong Kong, Macau and Taiwan are all technically part of "China" and fit the criteria well. Of these, Taiwan is the best place to teach English (highest pay, etc., unless you're very highly qualified / credentialed, then maybe Hong Kong would be better).

Overall, I think Taipei, Taiwan would be the best place for you to look into. It does get cool in winter, but I'm pretty sure they have heating. It's also the friendliest, coolest place in greater China, in my opinion. Lots of expat English teachers, chill atmosphere (certainly compared to any where in mainland China). Relatively unpolluted - best air quality compared to other cities in China or indeed Asia (only Japanese cities and Singapore have cleaner air, I think).

Taiwan also has nice beaches if you're willing to travel a bit. So yeah. Good luck!

Since when was Taiwan part of china?

Right. Well, that's the official position of both the government in Beijing and the government in Taipei (as well as the UN and all but a handful of countries in the world). It was a part of China in 1895 when China ceded it to Japan after getting its a** kicked in the Sino-Japanese war. It was also given back to China (the Kuomintang "Republic of China" government, to be exact) in 1945 after the US took it from Japan. And it is still officially called Republic of China. Almost all Taiwanese people speak Mandarin and/or another Chinese language and consider themselves ethnically Chinese, even though many are thought to have some aboriginal Taiwanese (polynesian) ancestry as well.

Having said that, Taiwan has never been a part of the "People's Republic of China", if only because the US navy prevented the communists from taking the island in 1949 (and ever since), and it's my impression that the vast majority of Taiwanese people are quite happy about that and would greatly prefer to remain a de facto separate country indefinitely, or at least until the PRC becomes more developed, democratic, etc. It can also be noted that Mongolia, Korea and Vietnam were all "part of China" for much longer than Taiwan ever was (roughly 1,000 years or so compared to "only" 200-300 years in the case of Taiwan). Russia separated Mongolia from China, as Japan did with Korea and France with Vietnam.

But I'm sure you already knew all of this. I'd be interested to hear your thoughts on the matter.

And remember, I did say "technically".

Just remembered something funny... Years ago at college, a PRC official came to speak about something China-related... I don't remember the exact topic. But afterwards, I went up to him and asked:
"I was wondering, what is the richest province of China?" and he answered
"hmmm.... that would probably be either Shanghai or Guangdong" to which I replied
"so you mean that Taiwan is not a part of China?"
HA! I was so proud of myself. :)

(for those who don't know - the PRC government considers Taiwan a rogue province of China, and Taiwan has long been more developed and richer than any part of mainland China)

His reaction was actually pretty subdued - I obviously caught him off guard, but he didn't get angry or anything - he seemed kinda like "hmmm", sort of nodding acknowledgment that I was right or something.

It was really a no-win question for him, because if he had answered "Taiwan", that would've been highly embarrassing to admit that "capitalist, colony of American dogs Taiwan" was actually more developed, more successful and richer than any part of communist China. But his answer unintentionally showed that even PRC government officials recognize that Taiwan is not really "part of China".

Zhuhai is worth considering - its nice beaches are miles out of town or on one of its many offshore islands, However the rest of the conditions meet your criteria.

Thankyou for all the invaluable information given :)

You're welcome - let us know what you decide!