How do the same pages, but with different cities affect SEO?

Question

Search Engine Optimization

I heard the opinion that the same pages are bad for SEO and that contributes to the deterioration of site performance. But, there is a familiar site where there are about 5 pages for different cities. They are the same, just the names of the cities change in the title. And there are clicks through the search, there are enough of them
. So, do identical pages harm or, on the contrary, improve the results of website promotion?

Answer 1

If the pages do not differ informationally (for design / templates - robots do not look): the text information is the same or the text difference is less than 50% (tags are looked at only when the text is in order) - this is considered spam and immediately ALL such pages fall under the filter PS.