Sure, someone on-site would be in your sight, but the role's ... on-site. "Site" is a place; "sight" is vision.
I am often tempted to correct "stationary" to "stationery" when the person means writing paper - I mean, it's definitely standing still (stationary), but can I write on it (stationery) ?
It's not about being intelligent; it's about knowing the difference and being able to catch it without relying on spellcheck.