Enabling WB_DEBUG and Activating Themes

Newbee to WordPress here. I have enabled WB_DEBUG in order to test a new plugin I am creating. I noticed that when I activate different themes some of them produce a lot of warnings, ie. deprecated function stuff and other errors. Most of these themes, I am assuming are up to date. Does this indicate these themes are buggy and have not been kept up to date and should be discounted? They still seem to work fine. Also, I have noticed these warnings/errors in many plugins I have examined and some of them don’t work fine. Anyway, as an old programmer these warnings/errors “bug” me. Obviously, WordPress is a very tight little engine and is robust enough to handle it all…