Clues — not proof
A wall is more likely to be load-bearing if it runs perpendicular to the floor or ceiling joists, if it stacks over a wall or beam below, if it sits under a second floor or roof ridge, or if it is thicker than a typical partition. Exterior walls almost always carry load. Walls that were added in a remodel might, or might not.
None of those clues is a substitute for tracing the load path. Joists can change direction. A 'partition' can still pick up a point load from a beam above. Previous owners cut things they should not have cut.
Why guessing is expensive
Take out a bearing wall without a designed beam and the house will tell you — eventually — with sag, cracking, or a header that was never sized. The cheaper path is an engineer who looks at the framing and, if the wall is bearing, sizes what replaces it.
Bob does this as an inspection, a design, or both. You talk to the person who will stamp the letter.