QUOTE: “One of the difficulties of running a great website that focuses on UGC is keeping the overall quality upright. Without some level of policing and evaluating the content, most sites are overrun by spam and low-quality content. This is less of a technical issue than a general quality one, and in my opinion, not something that’s limited to Google’s algorithms. If you want to create a fantastic experience for everyone who visits, if you focus on content created by users, then you generally need to provide some guidance towards what you consider to be important (and sometimes, strict control when it comes to those who abuse your house rules).”
QUOTE: “The quality of the MC is an important consideration for PQ rating. We will consider content to be Low quality if it is created without adequate time, effort, expertise, or talent/skill. Pages with low quality MC do not achieve their purpose well…. Important: The Low rating should be used if the page has Low quality MC. ” Google Search Quality Evaluator Guidelines, 2019
The SEO starter guide describes much of what your SEO will do for you. Although you don't need to know this guide well yourself if you're hiring a professional to do the work for you, it is useful to be familiar with these techniques, so that you can be aware if an SEO wants to use a technique that is not recommended or, worse, strongly discouraged.