I personally joined a startup dynasty league my first year in dynasty and than another the following year. After that experience I wanted the challenge to take over an orphaned team. Sometimes it’s rough with a bad roster. Sometimes the owner just lost interest. An orphan team doesn’t necessarily make it bad.
I took one of the orphaned teams to the championship and won in year one. The other is a rebuild that I’m excited to cultivate.
My best advice if you do take the ‘orphan challenge’: decide whether it is a contender asap. Seek out advice or evaluation from a third-party. The sooner you decide the easier as all future decisions will be in order to achieve that goal.
For example, on a contender you tend to reject trade offers for your studs. During a rebuild you can take more risk when accepting trades for injured/out of favour players.