This happened to me a while back but I thought it would be good to share to possibly save someone 10s of thousands of dollars.
I had some foundation cracks and a few small cracks in the drywall of my house. I got worried and called out a foundation company that offered a "free" inspection. The inspector proceeded to tell me that my house was "sinking and breaking in half like the titanic" and I needed $25k in repairs. I became very stressed. With a repair that large, I wanted a second opinion.
I hired a proper structural engineer. It wasn't cheap, he charged me $450 to look around for about 15 minutes. I had told him what the foundation company had told me and he laughed. I ended up needing no repairs besides a point and retuck. The cracks in the brick? He said those were cracks from thermal expansion. He saved me about $24.5k.
I later read that a lot of the "free" foundation inspectors operate on a commission basis. They will always tell you that you will need foundation work, otherwise they would be going out of business. Beware of free inspections.
Oh man, I can second the tree removal experts. We have a corner lot with a lot of large mature trees, and we get tree services knocking on our door monthly, telling us we should cut all of our trees down to “protect the house”. We were concerned enough to hire a certified arborist who worked with an engineering firm, who came out for a couple hundred dollars, assessed our trees, and told us all those companies were morons and our trees were just a bunch of nice healthy oaks.