There's nothing wrong with reading "pulp" novels. They may not be pieces of art but you're not looking for art, you're looking for language. I have read two novels by Oksana Robski (the two "Casual" novels) which are absolutely not what I would read normally, but they make use of everyday language. Then novels by Sergei Lukianenko and Dmitri Gluchowski, both authors write fantasy / horror / SF, also using modern language.

On the other hand I am currently reading Akunin's Pelagia novels, and while they are contemporary they are set in the 19th century, and the vocabulary shows it. I was told in e-mail conversation that I was writing like a 19th century duke because I used a couple of words from there which the dictionary did not mark as obsolete...

And with the Classics it's just the same. For a language learner who wants to learn contemporary language they are not the right material.