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

Serious disappointment when the client cancels a session.

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

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

If James Bond is meant to be the best secret agent in the world, how come all the bad guys in the World seem to know who he is?

Obsessing about clients outside of work hours.

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

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

Why do you think it is bad to allow people to self-identify as a different gender?

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

Off the top of my ancient head:

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

What legal actions can be taken if a neighbor's unleashed dog causes harm or injury?

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.

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

General Introduction to Boundaries from Panahi Counseling:

How often do prisoners try to escape from jail/prison, and how many of them succeed?

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