Earlier quoted context omitted.
Certain medical products, various hygiene supplies, or other things that cannot be talked about in 'polite society' would fall into the realm of things that are very hard to spread by word of mouth. Additionally, things that are rarely used by a person but are widely used by society, like stump removal services, plumbers, etc.
All of those can do just fine with a general search engine. You just need to know that removing a stump is generally possible. That fact itself can be advertised by a the guild of stump removers if it is obscure enough. "Tired of hitting your toe on the stump in your backyard? Ask you doctor for an eye check!"
What?