[delacroix01]

Well, there's all kinds of speaking in anime. Even in battle anime where many characters speak vulgarly, you can still find at least one who speaks politely. It's not uncommon to see a character who addresses herself as わたくし and uses いたします in her conversations, especially when she's a rich lady. It's obvious that IRL people don't pronounce clearly like anime VAs at all, but I think it's not a waste. By making yourself familiar with the clear sounds, you can later recognize them when people speak faster. I started practicing my listening with anime, and now I can get the gist when watching some dramas (of course I still need to re-listen many times if I need to understand the whole thing).

Speaking is different, though. It's important to double check instead of copying the characters immediately, since anime characters sometimes speak non-standard Japanese (like じゃありません), probably because the creators made them that way.