Im going to give this a run through as I have been pushing my design/marketing company more as of late.
I know, I never, ever use any form of "under construction" notice when I create commercial sites. Its the type of outdated nonsense that went out of style almost a decade ago.
Its either fit to be seen by your customers/clients or its not.
That being said - I wouldnt be surprised if many of the results that show up are being made by the business owner, have been "under construction" for years or are being put togther by some hack. So a good sales letter backed up by a solid portfolio could be a godsend to some of these business owners