What style of music are you playing? Your question mentions nothing of this aspect of the music. Furthermore, scales are great for practice, technique and theory. However, it is somewhat limiting to view an improvisation as simply the correct application of scales. After all it is possible to play all of the correct notes in the proper places and still sound like crap.
The tendency is very strong to become a "scale" player (beware the Dark-Side). Nothing is more nauseating than to visit your local guitar store and watch one guy after the next walk in, plugin into some effects and an amp and start ripping off solos that are so obviously nothing more than some dumb scales quoted almost verbatim. Even worse is the inflated ego that accompanies this performance! Meanwhile, the poor guy behind the counter is shaking his head cause he's probably the 100th guy that day that came in and played similar sounding crap!