I have said it many times… programming is easy. It’s easy to just write a few classes, add functions and have a running program. Anyone can learn that. However, to program well, you have to be able to design classes that have good structure, are easy to modify, easy to understand, and are able to withstand business changes. Now, to do all of that well is hard. Very hard. Object oriented programming helped in that area. But to do it well is also hard.
To me, Robert Martin has had the most influence on the OO world. The OO principles/patterns he created are hard to understand. But they are timeless and fundamental. If you learn them, follow them, and can identify them in your code, then I think you are a good OO programmer. If not, keep learning.
I was happy to come across this site that lists all of Martin’s principles. Study them. Learn them by heart. And start using them. You will become a better designer. Only after you master them, I think, you can call yourself a good OO programmer.
If you have not seen the books I recommend, I truly recommend reading Martin’s book, Agile Software Development.
I also recommend reading anything Uncle Bob writes. You will not be dissappointed.