"I love watermelons."
Translation:אני אוהב אבטיחים!
At least where I live, no one speaks like this (in Hebrew). If you like food, it's in the singular:
אני אוהב אבטיח, אני אוהב בצל
In English on the other hand singular is not used (it's awkward to say "I love a watermelon." as a standalone sentence).
I therefore think that in such cases (and I have encountered at least one more), both singular and plural should be accepted.