In single player then I may do if it's not intended. If I know it's there then I won't use it, but if it's an accident then I'll take the advantage given. For example, when playing Kingdom Hearts recently, when fighting Captain Hook, I stumbled onto a glitch where Hook just stayed in one spot spinning all the time and not doing anything, similar to the Goldeeye glitch. I was therefore able to pummel him completely with no health loss or anything. Epic win.
In multiplayer, however, then using any type of glitch is cheating and should be an instant ban from the server. I hate people who glitch or cheat in any way on multiplayer, it just ruins the fun for everyone else...