What are some signs that a therapist may have poor boundaries with their clients?

Obsessing about clients outside of work hours.

Sense of competition with persons who are important in the client’s life.

Frequent phoning or texting of clients to “check up on them and make sure they’re OK.”

‘King of the Hill’ voice actor Jonathan Joss is fatally shot in Texas - The Washington Post

Disclosing feelings, fantasies, and experiences to the client in ways not related to the work the client is engaged in.

Eager anticipation (or anxious anticipation) of the next session in ways that distract.

Struggling with fantasies of deeper connections with clients, whether sexual or parental or other intense or intimate relationships beyond psychotherapy.

What is the experience of wearing a school uniform every day? Do people typically get used to it or dislike it?

General Introduction to Boundaries from Panahi Counseling:

These items can happen fleetingly, briefly, in any therapy, but if they’re frequent, it’s definitely time for the therapist to get some good, solid supervision/consultation.

Failing to mention the client in supervision/consultation, out of fear the supervisor/consultant will advise return to ordinary healthy boundaries.

Why do wokes use words like "homophobes" when they don't know what that means? Do they realize that no one is afraid of them?

Routinely going over the time limit with certain patients, compromising the time for the next client.

Off the top of my ancient head:

Serious disappointment when the client cancels a session.

Has your wife or girlfriend ever been felt up in public by a stranger?

Session-expressed curiosities about client details not relevant to the therapy.