According to the SL page for Korean Go Terms, Soksu is written 俗手 in hanja. Assuming that there is no major difference between the meanings of hanja (Chinese characters in Korean) and kanji (Chinese characters in Japanese), then Soksu simply means a "vulgar play". In Japanese, the phrase is usually 俗筋 (vulgar technique).
Therefore, while a soksu may indeed involve aji keshi, it is not at all the same thing. (Or am I just speaking out of my hat?)
--Tamsin
quite likely ...
If a linguist can confirm, we can merge these pages.
Dieter