Dating last referrers
In fact any person who can benefit financially, in any shape or form, by sending fake traffic can send fake hits to your GA account.
Of late fake GA hits were also used to promote propaganda.
Bots are generally used for web indexing (indexing the contents of websites).
It is not very hard to artificially inflate organic search traffic in GA and then boast about one’s marketing efforts in front of client/boss.
But I am confident that Google is smart enough to detect what it is crawling is a log file and not a real web page and thus devaluing all backlinks from server logs.
This was in the form of language spam to vote for Donald Trump in the US election.
A bot is a program which is developed to perform repetitive tasks with high degree of accuracy and speed.