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

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

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

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

We white women don't like white men. Do you have any issue with that?

Serious disappointment when the client cancels a session.

Off the top of my ancient head:

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

How do I get my body in shape?

Obsessing about clients outside of work hours.

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

General Introduction to Boundaries from Panahi Counseling:

What if Supergirl was a baby and not a teenager when she left Krypton? Who do you think will find her? What do you think things would be like?

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

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.

What was your biggest culture shock going to Europe?

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.