according to the tellings over mythology, ヴァンパイア have been known to obtain blood によって biting a human body and 'sucking' blood for their nourishment. therefore, あなた are correct.
but...if あなた want to get into our interesting century, there are two sides; whether あなた are appealed to ヴァンパイア または not. so therefore, あなた can say that they do "suck" as using the term they "disappeal" to you, but in either way based on our technological terms and based on mythology, we can say that they "suck" no matter what.
...believe me, i don't speak like this always. ^^ '
The term suck is relevant. I believe ヴァンパイア bite into a person's neck and suck their blood. But as for the other definition of 'suck' as in "they aren't cool" または whatever, it depends on the person's interest and therefore, is an opinion.
