Most of the seduction is incidental. They don't want to seduce humans, but end up doing so anyways. Most Imperials are dirty/stinky, overworked, sick, mutated, starving, pustule covered, toothless, and look like they are in their 60s by the the time they hit their mid 20s (which is right around the time most of them drop dead from a life of drug fueled 20 hour per day shifts anyways). This of course has a huge impact on their beauty standards, as what would be a 2 or 3 here would be a solid 8 or 9 in the Imperium. By modern standards, Eldar would be at their lowest, an 11/10, so figure this into Imperial standards and you'd have a lot of Imperials guiltily committing all sorts of mental heresy.