Well lets say it is just the perception of that brand more than any negative experience with their TV per se (other than the experience with their mediocre quality Iron box which broke on me 3 times in the first 3 months) They are seen as a general consumer electronic company making everything from CFLs to Iron boxes and TVs, but not really good at anything specific.
Toshiba, Sharp etc have lot of experience in video processing and hold many patents. Whether these matter much when you are buying a consumer grade TV from them is questionable though

. Although the products may be designed in Japan, manufacturing is outsourced to some unknown companies in India. Sometimes the same company may be used by Philips also.