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

Obsessing about clients outside of work hours.

General Introduction to Boundaries from Panahi Counseling:

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

Why are so many US conservatives in this day and age still against racial mixing? They won't say it in public, but they are still against the mixing between Blacks and whites? Why?

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.

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

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

Why does it smell so bad? I noticed that when I move around my vagina has a stench. It’s usually a wet liquid, almost like pee. There’re little to no discharge and it doesn’t hurt or itch.

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

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 do Trump supporters believe Trump should deport the immigrants? These people you call "illegal immigrants" have lived here for many years, they have houses, jobs, how can you think they will just go back to their country, where they have nothing?

Off the top of my ancient head:

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

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

Do you think that the Democratic Party of the USA is not fighting back against Trump? And if so, why do you think so?

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