Agreed, Shatabdi's hideous ads make it look worse. Ads covering the entire exterior are fine, but those Canara bank ads are just terrible. With the reducing rake size (just 9 CC and 1 EC now, the surplus CC coaches were given to Karwar Intercity, Shimoga Intercity, Lalbagh and who knows where else), the addition of a dirty LSLRD in place of an EOG, all these changes make the Shatabdi look like it urgently needs some attention in the depot. In my opinion, SBC CDO's maintenance has to be taken up a notch (only for the exterior, most trains are still great on the inside). Even Rajdhani looks really dirty these days.
BBQ...
more... has historically been not-so-great (one look at the Double Decker will tell you), but the Mysuru Shatabdi and Brindavan have been maintained pretty well in the recent past.