Most people call this "black hat SEO" and "white hat SEO." As with most things, it's not quite so binary a situation.
Even so, breaking it into white and black hat ignores the likely larger problem of ignorant SEOs - those who think they know what they're doing but are completely worthless. In my experience, most SEOs who take "black hat" tactics tell their clients. It's the ignorant SEOs that waste the time and money of legitimate businesses and earn a bad reputation for the industry.
Even so, breaking it into white and black hat ignores the likely larger problem of ignorant SEOs - those who think they know what they're doing but are completely worthless. In my experience, most SEOs who take "black hat" tactics tell their clients. It's the ignorant SEOs that waste the time and money of legitimate businesses and earn a bad reputation for the industry.