1) Shabby Equipment
  The first signs that a company is a fly-by-night
  outfit are poor personal appearance, shoddy
  tools, filthy or broken equipment and vehicles
  in poor repair. Not every good construction
  company will have uniforms, new trucks, cell
  phones and laptops. (Some superdependable
  subcontractors we work with don’t even have
  fax machines.) But how a contractor presents
  himself and takes care of his truck, tools and
  equipment is a good indication of how well he’ll
  take care of you and your job.


2) Up-front payment
  "That's gonna involve a lot of materials. I'll have
  to ask you to pay me now."

  Requests for up-front payment before work
  begins should trigger a warning bell. Many
  people pay up front for work and then never
  see the contractor again. You should pay in
  advance of work only when it is a large job,
  you have already properly screened the
  contractor (checked references, etc.), and
  you have a proper contract. Upon signing
  the contract you might pay a percentage of
  the total amount -- usually around 30%.


3) Refusal to provide a written guarantee
  "If anything goes wrong, just call me. You have
  my word."

  No matter how sincere the assurance might
  sound, never accept a verbal guarantee. If
  anything really goes wrong, you'll quickly find
  out how worthless words can be. Legitimate
  contractors provide written guarantees that
  specify what is covered and for how long.


4) Refusal to provide referrals
 "We don't give out customer names. We respect
  their privacy. You understand, don't you? I'm
  sure you wouldn't want me to give out your name
  to strangers."

  Avoid contractors who refuse to provide
  referrals. Legitimate contractors are happy to
  name satisfied customers. Typically, it is with
  the customer's permission that his or her name
  can be used to recommend work to others.


5) No identification
  "Sorry. I forgot my business cards. You can
  always look us up at our post office box address."


  Legitimate contractors present themselves in a
  professional manner. They have business cards
  and an established street address -- not a post
  office box -- where they conduct their business.
  In an industry of many small independents, that
  street address might also be their home. That's
  OK. Self-employed people often work from a
  home office. What's important is that you know
  where to locate them if anything goes wrong.
  Be cautious of anyone who cannot produce
  identification. They could be transient operators
  -- people who work over an area, then disappear.