Maybe, for me, it's more a matter of not noticing any writing style at all; and instead, just "being involved" with what's being said. "Writing style" can sometimes be like make-up: It's OK that people see that it's there, but it's not supposed to be the first thing people notice about the wearer. :) Also, it's supposed to be skillfully applied.
Formula writing-style, "Internet-writing" style, copycat writing style (copying a tone and style that's very common among one kind of writer or another) - these are all examples, on the other hand, of "no writing style" of the author's own. I'd compare these to either no make-up or a bad make-up job. They're not all always awful. Sometimes they're only mediocre as far as writing goes. Still, these aren't particularly the kind of writing that appeals to me, as a reader.