She is rather a teenage girl stereotype who spends much of her time talking on the phone to school friends about their dates and her own activities.
She is a big jerk to Tom, mostly because she keeps hitting him with a broom even when it's undeserved.
She is not a good babysitter at all, because while the baby's parents are out, she regularly blabs on the telephone rather than doing her job. However, in Tot Watchers, she is far more neglectful towards the baby than she was in Busy Buddies, having made no attempt to look after the baby at all unlike the previous short.
On that note, she is extremely neglectful towards the baby in the latter.
She also hits Tom even when him and Jerry are trying to keep the baby safe.
When Tom and Jerry both do their best to bring the baby back home and put him in bed, Jeannie claims that the two were bothering the baby. However, it looked like they were stealing the baby, and wouldn't you mistake someone for stealing a baby at times?
She was never exposed as being a terrible babysitter.
She rarely babysits, so the baby is safe most of the time, and Tom and Jerry don't have to deal with her that much.
Despite her sub-standard babysitting skills, she is actually very kind and friendly and has many friends in high school.
Her design is decent.
To be fair, She just wasn't aware that Tom and Jerry were just protecting the baby.
She became one of the unfavorable characters in the franchise by fans, alongside Tom's notorious owner from the infamous Gene Deitch-era and Nancy from Baby Puss, although, as mentioned above, she's nowhere near as abusive as the other two.