Undead=Evil

[Jane_Smith]

They can still perform simple tasks that require no skill checks - like "patrol threw the sewers once after sundown, take trash to pits." Give them access to step ladders so they do not have to make climb checks. Or "patrol streets after sundown, take trash to pits, return at dusk", so forth. No skill involved - if a monster ambushes them they will just get destroyed, but if you keep your undead laborers properly numbered you can easily trace back where you sent it when it met its end and properly deal with the situation yourself.

As for crafting, skeletons can be told to aid in a craft check and aid another - with a single intelligent crafter at the lead it can be a rather potent bonus on a large project.