Cut the Blue Wire... No the Red Wire!

For me, the easiest way to finish this achievement was to...die.
You die near a gate under attack and you come back as a ghost. This way, you see every enemy and every bomb without being seen, and you just have to resurrect next to a bomb to disarm it (with the element of surprise, which is a plus).

Of course it's not perfect: with each death you'll have to wait more and more before you can resurrect but i managed to disarm about 3 or 4 bombs on average per battleground using this method.
Also sometimes someone loots your corpse and you can't come back as a ghost, but most of the time they are in a hurry to get another bomb, so they don't bother.

Remove your clothes if you don't want to pay for the repairs.

Not in the same game, thank god. Just disarm 25 bombs in total by right clicking on them.

ok you got me...i just want to see people naked. :P