"decorations" that aren't useful for the fish and that just take up room, anything multicolored rainbow dayglow, real shells and plastic plants! ugh
Yeah, I'm more of a natural looking tank gal myself, but I HAVE seen some with ruins, Budda's, and or Asian decor that I thought were very nice. But the rainbow stuff and skulls just DRIVES me! But that's just my opinion.
I like the Asian decor as well,, really inspired by the whole "aquascaping" thing,( if you haven't heard of it be sure to google it )
I guess i am also partial to "cheap" (ie terra cotta and floating plants!)
I bought a plastic cave once and it smelled up my tank of chemical plastic, fish loved it but I had to take it out, I let it leech out for 5 months and it still smells so i don't use it
However I secretly covet the human looking skulls alone in a tank with red gravel...