What is the consequence of "Mayim Genuvim Yimtaku"?
Sotah 7a: The Torah trusts a man to bring his wife alone to drink Mei Sotah; Chachamim enacted that two accompany them, lest they have Bi'ah on the way. One may be secluded with Ishto Nidah, for she will again become permitted to him. A Sotah might never become permitted! Also, "stolen waters (i.e. Aveiros) are sweet."
Rashi: Bi'ah with a single woman is not [as pleasurable] like Bi'ah with another's wife. Even regarding the Mitzvah 1 , they feared to do openly, and did covertly.
Malbim: Even though she does not give to him sweet wine and meat pleasant to the palate, and gives to him in place of them water and bread, since he received them b'Isur and via toil, they are sweet like wine. What is in one's Reshus and he is warned against it, it is sweet to him. Similarly, an Aveirah done covertly, with theft and b'Isur 2 is sweet.
Perhaps they enjoyed Mitzvos more because they concealed them from Resha'im who decreed against them. Or, the Mitzvos are sweet to Hashem, for they fear Him more than they fear the Resha'im. Or, Rashi means 'even regarding all Mitzvos (i.e. Aveiros)
