I think good traditional sencha should give clear transparent infusion. More steamed teas are cloudy as they contain dust.
Here is one description about quality 'metrics' (copy&paste from o-cha forum)
The leaves: the slimmer each leaf the better the quality. It reflects the tenderness of the tea leaf. During the process, old tea leaves will crack if intensive rolling process is attempted. Usually, tea leaves could not be rolled into fine needle shape and it becomes a flat shape or gets broken.
Using the early spring tea, thanks to the tenderness of the tea leaf, which is very elastic and can withstand the rolling procedure until a fine needle shape is formed.
The color of tea leaves must be dark green and glossy. Tea processed from the late harvest leaves tend to be grayish and light green in color with a dull appearance. This is because it contains less substances and moisture after undergoing the rolling process. Usually this tea gives a thin taste and cannot last for many brewings.
Japanese green tea does not maintain the whole leaf shape as cutting is part of the process after the final rolling.
Brewed tea leaves should be yellowish green in colour that indicates the young leaves are plucked. (Old leaves are green). When you hold the brewed tea leaf, it should be tender and soft.
The high end Japanese green tea gives a transparent and light yellowish green color.
Good tea leaves processed from the young leaves is tender and does not crack during the process. Therefore, it contains very little tea dust and gives a transparent liquor. On the contrary, the tea leaves produced from the late harvest leaves contain a lot of tea dust and that gives a greenish and clouded liquor.