There are certain facts about business and marketing that “everyone” knows, but are they true? Not always.

“Cyber Monday (or “Black Monday”)” is the largest Internet shopping day of the year. Think “Black Friday” (day after Thanksgiving, traditionally the nuttiest shopping day of the year) and e-tail it. Neilson/NetRatings even predicts and reports on the event. Well, gee, if Nielson follows the stat, then it must be true that Cyber Monday is the largest Internet shopping day of the year.

Not so fast, folks. It ain’t over yet. Turns out the Monday after Thanksgiving is more like a starting bell to the holiday season. You e-tailers may be able to catch a breath or two, but don’t let your guard down just yet. According to a BusinessWeek article quoting Comscore, it is - historically - only the 12th largest Internet shopping day of the year.

As with most not-quite-facts, there is bit of truth to the rumor. By most accounts, a Cyber Monday phenomen does exist, resulting in healthier single-day sales for online retailers.

Here’s another well-known “fact:”

Monday is the best day to email your business ezine, with Wednesday coming in second. Not according to a recent eroi survey reported by emarketer. Turns out Sunday and Friday ranked first and second for both opens and click through rates. If you read closer, however, you’ll notice the study did not differentiate between B2B and B2C newsletters, groups that - I suspect - have very different behavior profiles. The lesson here? Monday may not be the best day to send your newsletter. Sunday may not work best either. The answer? It depends. Your subscribers are unique, so test and see what works for you.

So what’s my point? In marketing, don’t automatically take established “truths” as fact. The real truth may have gotten lost in the retelling, times and customer / consumer behavior may have changed or your customers may not conform to the norm. In any case, question the “truth” and you may find a hidden profit opportunity.

[Technorati: Business, Computers and Internet, internet sales, email marketing]