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

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

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.

'No Kings' protests against Trump planned nationwide to coincide with military parade - NPR

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

Off the top of my ancient head:

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

Trump Plans Biofuel Quota Boost, Seeks to Crimp Imports - Bloomberg

General Introduction to Boundaries from Panahi Counseling:

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

Obsessing about clients outside of work hours.

There was this one weird Bollywood movie that was released in the 2000s. Amitabh Bachchan was starring with another actress and the story was about how the old guy (Amitabh Bachchan) fell in love with the young woman. What is the name of this movie?

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.

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

What exactly is the boundary men should follow while looking at girls so they don't call them perverts?

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