A box with suspiciously few images or text blocks on it is likely counterfeit. Most product labels and boxes (or other packaging) have a whole host of information printed on them, from bar codes and trademark and patent information to recycling symbols. Counterfeiters often don't want to spend the time to reproduce every detail, so they'll likely leave some of this stuff off. Also look for manufacturer contact information. Most reputable companies will provide a phone number or at least an address at which consumers can call them. China is the source of most counterfeit products. Of course, many legitimately produced products are also made in China, but a "Made in China" sticker on an already suspicious product is a red flag.  You should also be suspicious if no country of origin is listed on either the packaging or the product itself. Counterfeiting rings will sometimes remove a "Made in China" sticker when importing fake products, and producers of counterfeits will sometimes simply leave off the country of origin designation. Just about any product that could pose some sort of safety risk will have one or more safety certifications on its label. Some counterfeiters products may omit a safety certification label altogether, while others will often include fake marks on their products.  The UL (Underwriters Laboratory) label is the most common safety certification, particularly in the U.S. (the competing ETL mark is also a major certification in the U.S.). In Europe, the CE (the abbreviation doesn't officially stand for anything) marking is required on electrical products, and in Canada the CSA (Canadian Standards Association) mark is common. Look for at least one of these marks on electrical products. Low-quality products that don't claim to be brand-name may also simply use a counterfeit certification mark. Faked marks are usually, but not always, easy to spot. UL requires hologram marks for most products from China and for some products regardless of country of origin. If the certification mark is present only on the packaging, but not on the product itself, there's a good chance the product is fake.
Treat very plain boxes with suspicion. Look for a "Made in China" tag on high-end products. Look for a safety certification label on electrical products.