I've deleted a lot of spam entities in the last couple of days, but not all of the spam URLs get purged as they get unlinked from their respective entity. See:
https://musicbrainz.org/search/edits?auto_edit_filter=1&order=desc&negation=0&combinator=and&conditions.0.field=editor&conditions.0.operator=%3D&conditions.0.name=Freso&conditions.0.args.0=229784&conditions.1.field=type&conditions.1.operator=%3D&conditions.1.args=235%2C92&conditions.2.field=status&conditions.2.operator=%3D&conditions.2.args=2&conditions.3.field=close_time&conditions.3.operator=BETWEEN&conditions.3.args.0=2017-09-04&conditions.3.args.1=2017-09-08 - the ones with a clickable "info" link still has an URL entity, but if you look at the URL page, it isn't linked to anything (and doesn't have any open edits).

This is probably also true for non-spam URLs, but at least the spam ones would be very, very nice to get purged ASAP.