according to the tellings over mythology, ভ্যাম্পায়ার have been known to obtain blood দ্বারা biting a human body and 'sucking' blood for their nourishment. therefore, আপনি are correct.
but...if আপনি want to get into our interesting century, there are two sides; whether আপনি are appealed to ভ্যাম্পায়ার অথবা not. so therefore, আপনি 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 ভ্যাম্পায়ার bite into a person's neck and suck their blood. But as for the other definition of 'suck' as in "they aren't cool" অথবা whatever, it depends on the person's interest and therefore, is an opinion.