They spoil their site by sending spam

Granddads Life story is currently hosted on the business website http://www.rootskitchens.co.uk/family/les_root_story.php. There’s also a guestbook for people to leave a message and say hello. Despite it’s relatively low traffic there’s always been a level of spam that gets sent to it. When it happens I remove them. I was surprised today to be spammed by another furniture company. Their website looks pretty good too, I guess they are just trying to hard to be noticed. What defines spam for me? Well, it’s not relevant for a furniture company to be listing:
Oak furniture,tables,chairs.Bespoke furniture,tables,chairs
along with the website URL in a guestbook for a life story.
I guess they thought the guestbook was related to the business site in some way.