The examples of stupidity that I like were from the old nid dex- hormogaunts wouldnt look upwards and so couldnt go up to the top floor.. while normal gaunts obviously were more aware and so could... its still true with the new dex with raveners and warriors- having a tail means that you cant slither your way up to the top floors of ruins. Its not because you cant go up stairs/ladders because you can make it to the first floor... just not hte top (obvious the fear of falling off is too much if you have a tailk, even if you are fearless).Interesting... I can understand why someone's horse might not move up a level and why regular bikes can't get up there, but Fiends of Slaanesh and Thunderwolf Cavalry both would like to disagree with this rule (even though they can't, since they're just little plastic models.
Thats fine, as long as you dont play dicks. There are a couple of guys at my store who would declare that they were multi-level (even at the game start) just because the other player has a lot of beasts... these sorts of player are everywhere and are the sort of people who absolutely insist that they are not mulit-layer if they ever scatter a blast weapon from one 'layer' to the next (so that its over models that it technically cannot hit).Warriors are fine on rooftops and ground floors. It's the floors in between they have problems with - although they can move up and down through those floors quite happily.
As for the whole 'hurp-derp this terrain is a ruin with multiple levels' thing, make it clear before the ame to avoid that kind of thing. This is a ruin with this as a floor, this as a floor. This is area terrain, single level. That kind of thing.