A bruised LCD display could impair the functionality
Ideally the user should take care of his cell phone. First thing is keeping the phone in cover, when not in use. Second thing is touching the screen. LCD display is touch sensitive and it doesn't require much pressure but some users beat it when typing a message or entering a number. In the opinion of the phone engineers, beating it with finger pores is the reason behind the scratching and bruising of the it.
Taking out the phone from cover and putting the device inside after use also causes damage of it. Every time the phone is dragged out and slipped inside the cover, the screen is rubbed against the cover. You need to take care when keeping the phone in cover but it is not possible to prevent it from rubbing against the cover, however careful you are.
What a user can do is he can reduce the damage to the LCD display by taking utmost care. Thinking that you can keep the display look young forever is simply not possible because it comes into contact with external elements like sunshine and moisture when the phone is in use. You have to refresh it after a certain time period. Refreshing the it could be expensive at a retailer's facility but is affordable at any of the reliable shop.
Engineers at shop works on every make of Apple phone. They have the expertise, equipments, parts and experience needed for refreshing a bruised screen. The repair work is so carefully done that the repaired phone shows no sign of reworking or fatigue.
Apple users need not to worry about it as they can make their cell phones new by investing a little money in refreshing the LCD screen of their phones. The job is done at iphone shops and you can expect the job to be completed within an hour. Engineers might take some time in fixing a broken piece of it but, they don't take more than 24 hour in fixing or refreshing a screen.