Why can't I find a thorough house cleaner?

If you live in Denver and have a house cleaner you'd like to suggest, please help me out! I've lived here for 5 years and haven't been able to find a consistent house cleaner that I can stick with. These are my wishes:
1. Honest - trustworthiness is a must
2. Insured - not everyone is
3. Thorough - attention to detail
4. Services downtown area