What kind of spam is this on our form?
They're probably just testing your form to see if it is vulnerable. If it succeeds your site probably gets added to an automated tool and then will get "normal" spam on a regular basis.
The spammer is probably following this pattern, adapted from legitimate SEO folks who test Google indexing:
- Find a few long strings that return no Google results.
- Submit the strings to your form
- Search Google to see if the content shows up in the search results now