Safe to buy Ghosts (Row Key) from steamtrades ?

Is it ever safe? No

if the guy goes first and the key works, i guess.
Then again the whole rep thing is iffy. Best you can do is look for a veteran trader and hope he doesn't screw you over mate.

Warning: Ghosts is the worst COD game released for PC. You could buy better things, just saying.
As for the question I've traded for keys alot and haven't been scammed, guy with the key should go first and should have alot of +rep.

See if you can find a steam gift rather than a key. If anything goes wrong, you can get your keys back.

If he's on +147 is sounds pretty safe. Check if his comments comes from at least few high-reps too.

as a trader with 200+ on steamtrades i wouldnt recommend you to trade for keys. Gifts not always safe, but keys has higher chance to be bought using Carding or Skimming.

Call of Duty 1 = Call of Duty: Ghosts

That's all you should know.

Better buy Carl on Duty: Black Cops