Just take a quick look at all the mega sites based on generic terms; Cars.com, Hotels.com, Loans.com, Tires.com, Tickets.com, Books.com, Homes.com, etc. I think it all depends on the nature of the word...most generic single-word product names are better suited in plural.....cigar vs. cigars, guitar vs. guitars, computer vs. computers, picture vs. pictures, etc.