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

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

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.

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

What is the most popular song that includes the word "you"? Are there any other songs that use "you" multiple times?

Off the top of my ancient head:

General Introduction to Boundaries from Panahi Counseling:

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

Craig admits to 'illegal move' in controversial 'no contest' - BBC

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

Obsessing about clients outside of work hours.

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

While wearing high heels and walking heel to toe, when the toe box hit the floor there is a noise. How do I keep the noise just for the heel?

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

Serious disappointment when the client cancels a session.

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

Why did Sumire's summoning Nue act strangely in response to Kawaki's karma?

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