If a contractor is not reputable, he will try to cover his tracks any way he can. Using an online classified such as Craigslist, or even a website is the best semi-anonymous way to market your services as a contractor. However, when an investigation requires finding the physical location of such a business, it can be a challenge. The WHOIS lookup is a powerful tool at the investigator’s disposal in helping to find out the whereabouts of a business:
When you see a website link in your address bar that begins with http://www, and end with .com or .biz, then that name was purchased and assigned to a business and/or individual. The part to the right of www is called the domain name. To find out who/where/what the domain name is assigned, you can access a WHOIS lookup page such as http://who.godaddy.com/. This one to me had the least intrusive advertising, if you don’t mind the occasional “enter this number to verify you’re not a spammer” prompt.
For example, a recent Craigslist ad for a painter appeared below, with a link to their own website
That link to the website can be looked up below by entering the domain name, and hitting Search. You might need to trim the first and last few characters before searching
Other WHOIS lookup services exist out there as well. However they all have varying degrees of advertising, of how much info they provide, and how annoying the formatting is. Just search on Google for WHOIS and you’ll see all of them.
UPDATE: Sometimes the Domain Registration is listed under a P.O. Box without any additional information. That occurs when the website owner requested an “anonymous domain name registration”. There’s only one company that accepts these anonymous requests, and their website is DomainsByProxy.com. If an investigator was to email them with a request, stating that the purpose is to identify a fraudulent ad / service, then they will be happy to help you out.