I have been a CFI for 36 years, and have given countless flight reviews. If you do not feel comfortable signing them off, then don't. NEVER be coerced, guilted into signing someone off. Just give them an honest assessment of their flying qualities and sign their logbook as dual received. If someone can't own up to how bad they fly, then you don't want to be the one to sign them off, and then they go up and kill themselves, or worse yet, someone else. I also gauge the ride by what ratings they hold.