I have to as sitEponit seo’s how the heck is domain name like this created - — contemporary-furniture-designer.homedecor4us.com - the dashed and then the dot … is a a common practice or SPAM … 
It is a common practice and it is don’t with mod_rewrite (if you use apache servers)
This type of addresses are easier to remember for human beings than 123.domain.com. We’re better with words than with numbers. That means that if more people remember it, more people will visit your site and more traffic.
It is unusual to do something that long in a subdomain, like your example shows. Domains and subdomains work better if they’re short.
But it is very normal to do it in the environment of a CMS where posts are kept and you want people to visit those posts. Something like domain.com/category/title-of-the-post
Sounds like it might be a blog redirect trick - correction me if im wrong - is this done in the wordpress section of blog or on the server - curious to the effect of seo - if thats can improve ranking ide be inclined to do a follow up and use it to the advantage …
I suppose the owner of such domain name is building a chain of the sites for SEO purpose.
I’m not sure if you can consider that as a kind of spam.
But if that is possible that would be good idea to ask provider directly about that
of COURSE building a chain of the sites for SEO purpose - it is for the content management side - the tricks used is what im more concerned about i as advisor mention above - can they show us how that is done in html - php or wordpress … 
Instances such as these are coming up a lot. Now I understand that it is all for linking and SEO. Would be really interesting to know how it is done in wordpress.