Lucrative can mean different things to different people
Some might view a lucrative practice as one that does a large amount of cosmetic orientated work, whereas others might look at a practice that does more endodontics and oral surgery as lucrative.
Other might just think a lucrative practice is the practice that nets a large amount of money after all the bills are paid
And still others might look at a lucrative practice as one in a smaller area with little competition and rarely any after hours calls
It's all about what one considers "lucrative" because all of those types of practices exist, and their owners all probably consider them to be lucrative, whereas others might not want anything to do with that type of practice