Minecraft Merchant Spawn?

I started in the beta time and played over Jaaahre.
Only in the last 2/3 not so active, so here and there but without informing me.
I have been there for about 1 week now and discover the development of the world that I see the traveling dealer with updating the village less and less.
Have read everything about him and can't find my mistake.
Question: At that time it was so that on half stone plates or steps nothing can spawn, is that still the case?
So that my underground excavations designed to prevent spawn.
only for the dealer, for monster it is too bright.
I've read 48 blocks around the player's spawn, so I'll take it up or down.

Nothing is spared when the steps are in the lower part of the block