I'm not terrible at French and still struggle sometimes to discern the word breaks. Malapropisms in my native English can arise from that too. Learning a new language it can be v. hard to distinguish word breaks - our brain fills them in when we know a language, which is why it's hard to imagine that people might not agree that "dog" is separate.

Try saying "Hangdogears". Is it "hangdog ears" is it "hang dog ears" is it "hang dogears".

(hangdog = guilty visage; dogears = folded page corners)

Try it on someone else and see how they interpret it.