i have a big problem explaining that clever and smart are 2 different meanings , most chinese believe they are the same word.

depending on the situation, calling me clever may actually be a subtle insult

You asked two questions, arguably related. As to the first; I don't know. I imagine that's not often true. I take every opportunity to praise their English when appropriate. I make it a point to compliment something about everyone when teaching English. No one wants public criticism when learning a language.

The second point may be explained by noting that some Chinese people think, or are maybe taught, that they are smarter than everyone else, and no one else can learn Chinese, thus if you correctly pronounce "ni hao" you might be praised. However, you claim that a foreigner speaking nonsense Chinese might be praised. I have never experienced or witnessed that. When I speak nonsense they correct me, or stand there speechless because sometimes my Chinese is so bad it's indecipherable.

Then again, they might simply be pleased that you bothered to learn some Chinese, because apparently many of us foreigners don't bother to learn any at all, so they say you're clever. I study characters (hanzi) on my own -  because I'm interested - and some students appreciate that. Also, it comes in handy when trying to read signs. And it looks cool. Hey, just my opinion. Dang this is long.

The question has no substance, since the person asking it displays poor ability in English, so therefore could not judge who has"fine English" and who doesn't. He probably thinks his own English is good.

In 10 years, I have met very few Chinese people who could speak good quality English. Maybe half a dozen, if that.

Speaking Chinese has no real benefit for most people outside of China, so no need to learn it. It is a nice party trick, though.

Only a very few Chinese people - some of my co-teachers - spoke 'fine' English, and they got there from years of study and constant practice, not out of inherent intelligence (although some of the girls were very clever).

Now, as to your question: "oh wow! You can use chopsticks.... most clever foreigner!!!!" Not really setting the bar very high, is it?

I am not going to give you my usual sarcastic reply

(only because I don't think you are Matty)

I think that Chinese are just trying to be polite when they say this and not always to blow smoke up one's Ass

We do not always praise the good English of Chinese  because we wonder what is coming next

I have yet to meet a Chinese person who thinks we are clever....

I have had it said to me a numerous number of times and it is usually after I have done something or prepared something using common sense. There is a noticeable lack of that in this country IMHO. In our country the use of common sense isn't accompanied by the exclamation: Oh aren't you clever! We just say: Hey, that's usin' your brains, mate!