It always hard. You can have the biggest, dumbest oaf that can't do a blessed thing, but when you have to tell them they are no longer needed or up to your expectations.... it's tough to do.
If the person has done mean or deceitful things and you have proof, then I'm like 'Just Another Sign Guy'..... I'll kick 'em to the curb and into next week. To me, that's stealing. Purposely lousing things up or not doing their job while getting paid and blaming others or lying..... well, they'll get it with both barrels.