Reservations about survey bias

Scenario
Sam, a therapist, wants to get feedback from his clients about how he is helping them. He considers several approaches to collecting the information. He rejects the idea of mailing people surveys because of the expense. He thinks about giving surveys to clients at the end of sessions and asking them to complete them, but he knows some of his clients do not read well. He decides the best approach will be to ask clients a couple of questions at the end of each session. Sam then considers what questions he should ask and finally decides on asking a series of yes-no questions:
1) Today’s session was helpful to me.
2) I feel happier after today’s session.
3) I feel stronger after today’s session.
4) I am glad I am in counseling.
5) I have gained from counseling.
Sam is surprised to find that his coworkers have some reservations about survey bias. Whose concerns do you think are most valid?
Ava worries that by asking the questions himself, Sam may inadvertently pressure his clients to respond in ways that reflect well on Sam.
Erik wonders if, by having all of the questions worded in positive ways, some people will have a tendency to just say yes to everything, especially when the person asking in in a position of authority.
Pam thinks some people might answer in ways that would make them look good, for example, by saying they feel strong and happy when, in fact, they feel vulnerable and discouraged.
Which concerns about measurement do you agree with the most? Provide a brief explanation and rationale (5-6 sentences).