Umpire's call for hot-shot, sounds, etc?

[CSK Fan]

I think for the LBW rules, DRS is pretty clear. Because of the uncertainty around it, decisions are only over-turned for obvious howlers, otherwise it goes with umpire's call The confusion with hot-spot etc, is that there is no clear cut rule of when to overturn and how much evidence is conclusive. Maybe we need something like umpire's call for inconclusive hot-spot too