As much as I do like to see many flashy and colourful liveries, it is rather annoying after the franchise renewals, where an operator is landed with stock in umpteen different liveries from umpteen different previous operators, and it takes absolutely years to re-livery every piece of stock a franchise operates. To put the cherry on the cake, there's then national stock reshuffles!
In ATWland when the 175's still had North Western's Barbie livery, there would be trains going through stations (to Manchester Piccadilly), only followed by NR 180's also in Barbie livery; one hell of a confusing situation. It took Arriva 6 years to re-livery the 175's, and they've still got one to go!
Arriva's stock in 2003 was composed of First North Western, North Western Trains, Wales & Borders, Wales & West, Valley Lines and Central Trains units, and to think a fair number of these are still in their former liveries seven years later, is rather outstanding. The stock reshuffles then added yet more liveries to ATW's pool! Its a mad mad process, that costs and wastes hell of a lot of money.
I believe each franchise should have its own livery, however these should be set and unaltered, besides the corporate name. National liveries are good, but I still think there is a place for a regional scheme.
What annoys me far more, is the constant re-branding of individual railway stations. Colour scheme after colour scheme. New signage. New fonts. New layouts. Its absolutely pathetic. I wish Network Rail would pull their finger out on their stations and stop this barbaric mess of chopping and changing what was a consistent system! And like train liveries, when a new franchisee comes along, the whole thing starts again, and its so inconsistent.