When I said the Alien salivates prior to attack, yes, that's in all the movies, but the way Ridley shot it in the Brett attack, head down with a couple of bits of dangling KY literally pumping and pausing and pumping and pausing watery goo like some lazy pre-ejacualtion seems far more bizarre and is echoed by the discordant pulsing in some of Goldsmith's music (particulary Parker and Lambert's demise).
This might by massively over analysing things, but it's those little touches that, yes, make the alien seem natural, like something shot by OSF, but also give it an extra level of alieness, whereas Aliens seems go for stringy goop, or stretchy gum-like deposits.
In other word if you're going to choose a lubricant go for KY instead of chewing gum!
Anyway, back to the OP. These touches that Ridley made and the slower more meticulous attack in the one really revealing scene do appear to give the creature more than just a natural hunter approach. I wouldn't choose the word evil really as that appears to belong in a different genre, but sadistic yes. The human DNA in it perhaps?
