A glitch is a bug or error in the game or map. It is not to be mistaken for an exploit, which is abusable to the benefit of a player using them or general griefing. A glitch would be along the lines of not being able to load a menu screen or jumping out of the map by accident. Before the july 21, 2009 patch xbox, players could modify the binary data in any orange box.
Many people get confused between lag and glitches before knowing about them. Do not fall for this trap as these users. Usually hacks are made to destroy the game and have unfair advantages or to fiddle with the textures of things that are. How an active trader don't knows about those guys.
Imo - people who are still getting scammed are ignoring stuff like help, guides etc until they get scammed. Well, it's your prerogative to scam someone.
A glitch is something wring with the programming of the game that causes you to be able to do somehting that otherwise would not be permitted. Glitches are different to hacks. You can buy scrap from websites that sell it, like tf2outpost, other than that you can craft, trade or.
Hacks are somehting that breaks the game and coding that was broken by a player of that game that causes thing that otherwise would never be able to happen.