Here is the dilemma: you need to let somebody into your house while you aren’t there for some reason, but you are worried that the key may be used for an ulterior motive. I have the answer for you.
1. The cheapest solution is to have a side or back door keyed differently. Make the doorknob work with a key you lend out but the deadbolt lock is thesame as the rest of the house. When you want somebody to be able to access your house, just leave the deadbolt unlocked. After the workman has finished his work, leave the deadbolt locked and nobody can enter with the spare key because the deadbolt is still locked.
2. A more elegant solution is to masterkey the doorknob. Then the doorknob can be unlocked and relocked with both keys. You can lock out people with the loner key with the deadbolt.
3. Another solution is to get locksets installed that are interchangeable core. Then you can change your locks at will. Change the lock for the day, when you get home change it back. This is probably too extreme for most homeowners and reserved for sufferers of paranoia and control freaks.
4. My favorite solution, a combination of 1 and 2, is to change your locks to use a restricted keyway and masterkey the doorknob on any door of your choosing. Then you lend out a key to somebody and they can’t copy it anywhere. I can supply you with the MX2 keyway, one which locksmiths and distributors are legally bound to not sell blanks or copies of. If you get MX2 locks from me, I write down your name and bitting and encrypt it using PGP. If anybody asks me to copy an MX2 key, unless I made it I will say no.
I can assist you in this matter using any of the strategies outlined. Keep a knob separately keyed and save $20 on rekeying. Have me rekey just one lock for $20. Installing interchangeable core locks is more expensive and worth an estimate.