I don’t want to generalise, but I think it’s quite safe to say Hong Kong people dislike mainlanders (people from Mainland China).
To the western person this may seems completely ridiculous since Hong Kong IS China, but let me tell you many, many, many Hong Kongers to not consider themselves Chinese. They argue that Hong Kong never was a part of China, since China as we know it was created well after Hong Kong.
Anyway, back to the main topic.
Hong Kong people foster a certain dislike for the population of mainland China.
As long as they stay in China, Mainlanders don’t bother Hong Kongers, but once they cross the border it gets a bit more…touchy.
The main reason for the disliking of Mainlanders is their lack of manners and politeness.
It is not rare (at all) to see videos all over the internet and the news of Mainland children eating inside the metro (this is forbidden) or peeing in public spaces.
Mainlanders skipping queues, talking extremely loudly and lacking general manners is not a rare sight in Hong Kong. However, I do think that Hong Kongers are overly sensitive to it.
It is not rare to see western tourists drink in the metro or even pee in the street in the wee hours of the morning; however this never generates heated arguments and viral internet videos.
These little “crimes” may seems ridiculous to get all angry about but this is coupled to some political stuff and high numbers of mainland emigrants, creating a general exasperation.
The thing is with these mainland Chinese is that they have become rich but are uneducated. They therefore believe that since they have money they can do anything they want. They also have not learned basic manners (since they have little education).
You may think I am exaggerating, but here a little example for you:
Jeff was on a boat and a wealthy group of mainland Chinese were on the boat as well.
The mainlanders did not sit in their assigned seats, creating a mess with all the other passengers.
The stewardess asked the mainlanders to return to their assigned seats, since the ship was full. They refused. As she continued to ask them to return to their assigned seats, one Chinese man got angry and PUNCHED her.
He punched a woman in the face because he did not want to seat in his designated seat. (He got arrested when the ferry arrived at destination, in case you were wondering).
If this had happened in a street in Hong Kong (as opposed to in the middle of the sea), I can guarantee that a mass protest would have taken place.
The thing is some Hong Kongers are starting to generalise the situation and sometimes can even be racist towards mainlanders.
Issues need to be solved quickly before things go wrong…
Nifty Pifty 
and btw. Hong Kong is NOT China, let’s not confuse people :)!
Agreed! I explained that in a previous post. However this is a concept anybody outside of hong kong struggles to understand.
and people wonder why Hongkongers don’t want to be seen as Mainlanders. there’s also another issue of cross-boarder mom’s, abusing the welfare etc., for me I don’t care if you’re a Mainlander, other foreigner or local – if you disrespect Hong Kong and people around you, you don’t deserve to be in that place. aside of communism that is slowly leaking to Hong Kong, if that kind of people will be anywhere outside they will only makepeople dislike Mainland Chinese even more – many places complain about Chinese tourist. I don’t say they are bad, 90% are normal, more or less, but 10% are f… up totally and ruining it for the rest. Camping in illegal places instead of paying for a night in a hotel when your luggage is full of luxury goods. Littering, spitting, squatting, arguing, not following the rules… I get that those 10% are farmers who just got paid for their land, but China for it’s own good should send those people to some manner course or something. and hitting a lady… God, I don’t even want to think about it. >.<