scanlines? You
must be kidding me.
G_Yoshi's logic is grievously flawed.
Unless your aesthetic tastes are unnatural, scanlines should only be used to resolve graphics problems on slower machines.
If you're playing an SNES game, my advice is to just expect it to be "pixelated." The SNES was a system for a television, and televisions have extremely low resolution- SNES games always run at 320x240 pixels, 256 colors.
However, if you must know...
You have two options to resolve it if you don't like the pixelated look. Edge enhancement and interpolation.
Interpolation fuzzes the game out so it looks more natural. You can achieve the same affect by scratching up your screen such that light will not pass properly through it.
Edge enhancement uses a little algorithm to "guess" at higher resolution by drawing diagonals logically. It looks kind of weird, but also kind of neat, and it does the trick