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

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

Off the top of my ancient head:

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

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

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

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

What is truer than that which is true?

Obsessing about clients outside of work hours.

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's an underrated/unknown novel or series that you think deserves more attention?

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

Serious disappointment when the client cancels a session.

General Introduction to Boundaries from Panahi Counseling:

If women see themselves as free, dignified, human beings just as good as men, can Trump hang it up and just lose in a landslide at last? How can men who like and respect women help improve womens' self-esteem?

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.