You know the old saying "You get what you pay for"?
Man businesses don't know the risks involved with hiring the cheapest janitorial service. They don't usually provide the best cleaning and may have to cut many corners just to make a profit.
When making your choices, consider that minimum wage has gone up in many states, and that most janitorial services pay more than minimum wage to get and keep good employees, So, they risk hiring untrained workers without a back ground check. This could cost you in the long run.
Another thing to consider is that the cheapest service may not offer liability insurance or worker's compensation. As many of you know - business insurance is not cheap, so be sure to consider that when you receive a bid that is much lower than others. Hiring a company that is full bonded and insured is more trustworthy and reliable.
Remember, your place of business has expensive office equipment in it. You also want to be confident that all your hard work is right where you left it the night before. That is why you hire people you can trust, which is probably not the cleaning service with the cheapest bid. Check their credentials and references!