I suggest "messy handwriting" or perhaps "untidy handwriting".

Hello Jessica, Never heard of 'ugly handwriting' before but Vicki's answers are both good and I would add illegible/unreadable handwriting. Best wishes Bob

Messy/scruffy/bad/etc

"ugly handwriting" seems a good candidate to me. http://graphology-world.com/ugly-handwriting-and-what-it-says-about-you/ Bye, tano