Taka said:
What is the etymology of such "suck"? I mean the bad one.
This is from an etymology dictionary. It attributes the negative meaning of "suck" to a reference to "fellatio".
suck - O.E. sucan, corresponding to L. sugere "to suck," from PIE root *sug-/*suk-, of imitative origin. Meaning "do fellatio" is first recorded 1928. Slang sense of "be contemptible" first attested 1971 (the underlying notion is of fellatio). Suck eggs is from 1906. Suckling is early 13c.
I've heard that before, but I am skeptical. Certainly there is no allusion to oral sex in its current usage. I have entertained the possibility that it comes from the horse world. There is a condition in mares called "wind sucking". This condition arises from poor conformation of the vulva and allows air and fecal material to be sucked into the vagina. This can lead to vaginal and uterine infections and infertility. Many US English idioms come from the horse and horse racing worlds. It is possible that the negative use of "suck" arose from bad mares that "suck".
Note: There is another condition of horses that some call "wind sucking"
that is unrelated to the condition described above.