How To Stop Advertising Posters?

I’ve belatedly realised that a lot of comments – the majority – are posted as advertising and they’re probably even done by a machine, software, rather than a person.

So I go through them and put them to trash. Which is very time consuming. How can I stop them at source? Is there some way for me to perhaps take certain words from their postings and ban comments that contain those words?

Now I find that even the comments I’ve let live present on the list of ‘recent comments’ with first of all a link to their ‘title’ or whatever followed by a link to the blog post in question. Now I’d like to remove that link to their ‘title’ which is usually their homepage, their website and is often just advertising…. they’re selling something and that’s the only reason they post on my blog..

Can I do that?

regards,

dh