Hum... From what I've read:
"The trainers for StarCraft 2 are now retired. The short reasoning is because of the Warden System.
The long reason.
Blizzard has an anti-cheating tool that is not unlike systems such as VAC Ban or PunkBusters or GameGuard. This system is affectionately referred to as The Warden Client. It has its roots stemming all the way back to Diablo 2 and the original 1998 StarCraft.
Warden has 2 main functions:
The first is the anti-cheating technology built into their games. For the classic Battle.net games (Diablo 2, Brood War, WarCraft III) and World of Warcraft, this client is built into the game and has some limitations but does help out a bit. For the modern games (D3, SC2, Heroes, etc) though, this is built into the Battle.net client that games run off of and is more of a layer of security between the game the server. Since it is a custom in-house solution Blizzard built themselves, they have a major advantage in tying it very close to their games making security extremely tight.
The result of that first function? If you cheat while connected to the game online, your account gets flagged, "reviewed" (likely automated process), and bans your account. Think of it like Steam's VAC system but on steroids. It is by no means perfect and there are plenty of people that really want their hacks. For trainer developers though, not many want to go forth the extra mile to essentially break/*****/whatever this game to do it.
Now the 2nd function of Warden which is optional although almost always included (and being included with LotV and the retroactive patches for lesser expansion levels of SC2). It is to force the game to always be online. Hence this makes getting around the above function impossible. Before you could go offline play but this is looking to no longer be an option going forward.
In short, it won't be possible to use a trainer and not get banned going forward and thus not feasible to continue trainer development."
Source:
http://www.cheathappens.com/show_board2.asp?headID=127958&titleID=21291
So, using a trainer might make your account be banned...