Cut out is always best. That way you clean out the hive and can properly seal any entrance holes and if need be fill the cavity with fiberglass insulation. Best part is the customer clearly gets to see that the bees, honey, comb, brood, etc is cleaned out.
But this means opening up walls, floors, siding, sheet rock, etc., etc., and the customer needs to understand that to be able to do a proper cut out you must be able to physically put your hands on the entire hive, not just be able to look at it from a distance.
Do not sell your services short either, remember they need the bees gone more than you need bees, stick to your guns and walk away if need be. If you spend 8 hours doing a cut out, figure in all travel time, cut out time, gas, etc., and put a price on that you could have bought a nuc for $125-$150 and not even broke a sweat. There is no guarantee the your cut out bees will make it either.
Trap outs are expensive on you, a minimum of 7 trips to complete one, and still no guarantee of a viable hive out of the deal.
If the bees have been sprayed, charge more. You do not want to be doing a clean out on sick, dying dead bees for nothing.
Good luck and post pics.