Pretty much everything you said is spot on, but there are cases where it can work.

A family member was set on purchasing a condo so we enlisted a family friend who was a realtor. The guy has experience and was clearly competent. My family just really needed him to help with basic paperwork and were thinking of doing the realtor a favor by giving him the easiest commission of his life. The realtor actually advises my family against buying it because of several risks he found during his research. Family disregarded it and went ahead. Two years later, everything went tits up for the exact reasons he found and family went through a lot of stress to fix things.