You assume the surveillance guy is watching your table closely and has reason to come in close to look at the player stacks. Most of the time the camera is zoomed into where the dealers hands are going and the dealers rack, not paying as much attention to the details on the players side.
The house "might" be able to make everyone whole, but they might not. If you walked up with say 14 red chips and 3 green ones, didn't stack them very neatly, took chips off the table here and there and put them in your pocket or toked a cocktail girl with them...they probably wouldn't count you 100% accurately. If you buy-in with cash and only use the chips to play, they obviously could count you perfectly, but other transactions would be tougher.
One positive though is casinos are usually very forgiving on these things and will tend to err on the side of the customers. If they say they think you had 14 chips and you insist you had 15 or 16, chances are good they might give you the benefit of the doubt.