A space $X$ is called weakly-Lindelöf if every open cover $\mathcal{U}$ has a countable subcover $\mathcal{U'} \subseteq \mathcal{U}$ such that $\cup \mathcal{U}'$ is dense in $X$.

This class seems to be of interest in functional analysis (spaces of continuous functions). Every Lindelöf space or space with a dense Lindelöf subspace (like separable spaces) is weakly-Lindelöf.

In this paper by Hajnal and Juhasz they construct a ZFC example of two Lindelöf spaces whose product is not weakly Lindelöf (a variation on the Sorgenfrey line construction). Besides this example and the obvious example of an uncountable discrete space, I've not been able to find non-examples, i.e. spaces that are *not* weakly-Lindelöf. Does anyone have any pointers to where to find more of those? To understand a class of spaces I prefer to have both examples and non-examples.

This paper by Frolik is supposed to have defined this notion originally, but I cannot read Russian, so I cannot check. Maybe the "seminal paper" contains more examples, I thought.