totally agree, once a restaurant gets an award or is famous, besides having to deal with the queues/overcramped 'tables" oftenly the service level goes down the drain too. (or they were cocky to begin with)
my local example is ho to tai has been around for at least 60 years and according to the locals THE must go to noodles shop in yuen long. i tried it a few times and didn't like it: overpriced and the dishes are so small that you still feel hungry after. i prefer going to this back alley noodle joint, sure it's not as clean but it's cheap and more importantly tasty.
I was referring to "The Square"
The Square - Guangdong Dim Sum Dim Sum Restaurant in Central - Hong Kong Restaurants Guide HK Restaurant - OpenRice in English
They also have great non dim sum dishes at night, I like it there coz their dishes are usually lighter and less "thick-sauce"-ish.
Another option nearby would be "Chiuchow Garden Restaurant" in the basement of Jardine House. They have other locations too.
Chiuchow Garden Restaurant - Chiu Chow Dim Sum Dim Sum Restaurant in Central - Hong Kong Restaurants Guide HK Restaurant - OpenRice in English
Lin Heung Kui in Sheung Wan is supposed to be the last of the truly authentic Cantonese Dim Sum joints in HK. I took my parents there once since it would be something they may appreciate from their youth. It's busy and loud, though I can't tell the difference between the food there and other good dim sum places... but my parents seemed to be impressed.
Lin Heung Kui - Guangdong Dim Sum Restaurant in Sheung Wan - Hong Kong Restaurants Guide HK Restaurant - OpenRice in English
"Fook Yuen Seafood Restaurant" at Kowloon City Plaza has good dim sum. All menus are in Chinese. But quality food.
"Dim Sum The Art of Chinese Tit Bits" at Happy Valley is more expat friendly.
When we are after a decent (not cheap) YumCha, we head to Metropol å都酒樓 in Admiralty.
If on the southside, then La Dynastie Restaurant 姬å皇æœ
Eventhough we live in Happy Valley, I've avoided DimSum in HV for the past 10 years as its too expat friendly; its always full of expats and no empty seats Its also very expensive for what it is.
I always fancied Lok Cha Tea House in HK park in central. Bit expensive but very good, and well it helps as they are a vegetarian joint.