One thing which is prohibited in seo services is the practice of keyword stuffing. If a company promises you a better ranking by using plenty of keywords in a single blog then they can’t be trusted.
There is a specific density of keywords that must be used as per the words of the content. If your blog is 1000 words then it doesn’t make sense for the keywords to be there 100 times.
If Google senses that you are indulging in foul practices to make your content rank then it can take strict actions against you. It can also take your website down from the internet. You should always stick to the word limit and include keywords accordingly.
At times, you might think that using synonyms will save you from the eyes of Google then you couldn’t be more wrong about it. You have to be really specific with the words and their meanings because one wrong move and your website can be gone forever.