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

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

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

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

Jewels sparkle like stars in Van Cleef and Arpels' 'Cosmic Splendor' at NYC's American Museum of Natural History - Space

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

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

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.

What's the most trivial thing that ever made you go to the doctor?

Serious disappointment when the client cancels a session.

Obsessing about clients outside of work hours.

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

Is it okay if I am not interested to talk to any of my relatives as I saw the real faces in my brother's marriage as none of them helped us rather were a kind of disappointment and were talking bad?

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

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.

Have you ever been instructed/forced to crossdress for the benefit of others?

General Introduction to Boundaries from Panahi Counseling: