I think they're talking about where you may select a different conversation option than the one your mouse pointer was on. Happens very rarely...and is easily fixed with about .3 seconds of mouse wheel scrolling. QQ'ers love to find anything to QQ about lol.
You're wrong. The dialogue bug is when any changes to vanilla dialogue result in the dialogue not appearing, no subtitles showing up, the npc not speaking, ect. It doesn't have much of an effect on console players, or people who don't use mods. But, it really messes with mods, and the USKP.