I generally don't clean up my hi-poly models simply because I won't be texturing or deforming them, and the AO/Normal map transferring process doesn't (in my experience) require the hi-res model to have clean topology. Even if I indend to take them into ZBrush to sculpt I'll be generating an entirely new skin for them when I get there anyway.

For my low-poly in-game models I'll always keep the topology nice'n'tidy

Martin.

EDIT: Feel free to say 'YOU'RE DOING IT ALL WRONG!' I'm still a newbie to all of this so any tips and pointers are welcome and greatly appreciated.

EDIT v2.0: Another render I did of the grenade, better showing the functionality and intended colouring,