I have a simple site using a customized version of Shopify's Brooklyn theme. My store is small: 2 products, and only one of them has a variant (t-shirt sizes). However, for no apparent reason (I know, we've all heard that before...), default text ("DEFAULT TITLE") now appears as a variant on the product that doesn't have any variants.
It's probably a quick fix in product.liquid or product-variant.js, but I'm not savvy enough to figure it out.
Want to make a quick buck?
John