Every entrepreneur has a dream of buying a company or investing in a start-up. But the problem is: how do you know which companies are worth investing in or purchasing? Nothing stings worse than pouring your money, time, and effort into a company, only to have it go belly-up.

Business-guru Noah Kagan recognizes this risk, and has explained key signs to look for when considering investing in or buying a small business. Of all the factors to consider, what might be the most interesting is to notice how said business is advertising. Are they advertising very little, or not at all? If so, now might be the best time to invest.

It seems odd, but it can actually be very telling about a business’s prospects when combined with other factors. If a business has profits that are either flat or at a slow incline (note: stay away from businesses with declining profits), and is also advertising very little, then you may have a recipe for success. Why? Because with the right push on advertising, combined with a proven viable business model, you may be able to push the profits from stagnant to soaring.

If you’re considering investing in a small business, be sure to keep a close eye on not only their profits, but also their advertising frequency—it just might mean the difference between a good investment and throwing away your money.