To what extent is hardly a negative adverb?
Solution 1:
Well, as you point out, hardly is a negative trigger.
I.e, it can license Negative Polarity Items in construction with it.
Any and at all are NPIs, but there are lots more in English.
Checking out the negative strength of hardly (as shown in this freshman-level puzzle),
we find that it works with some NPIs
- I hardly have any ~ I hardly ever do it ~ He hardly budged ~ He hardly has a red cent.
- He's hardly done it in weeks ~ They'll hardly arrive until noon ~ I hardly have much time.
but not so well with others
- ?He's hardly arrived yet ~ ?You hardly need stare at him
- ?I hardly dare disturb him. ~ ?It will hardly take long
and with still others, it's terrible; both of the following are ungrammatical, for instance:
- *I hardly saw people there to speak of
- *I would hardly mind fighting with her
So, to that extent hardly is a negative.
It's a strange word, and shares this level of negativity with seldom, rarely, and scarcely.
Solution 2:
If you check at say AHD, you will see that different senses are given for 'hardly'. Where I start to worry about their treatment is that they lump all of these usages in the 'adverb' catch-all, even though the distributions are easily separable.
Mary hardly laughed in the usually understood sense ('Mary hardly laughed at all') certainly has 'hardly' associated with the verb 'laugh(ed)', but I'd say this is not a true adverbial modification (saying something more about the manner say of laughing) but telling us more about the limits of the action. It seems to be the verb-related analogue of 'a determiner rather than an adjective', referencing the context of the verb rather than truly modifying it. I'd class it as a limiting modifier here. Compare 'John almost died'.
On the other hand, Putin is hardly popular among Germans uses 'hardly' as a modal pragmatic marker being dismissive of / assigning near-zero probability to the statement in the main clause (as seen by the rewrites 'Putin - popular among Germans? Hardly!' or 'One could hardly say that Putin is popular among Germans). The first rewrite possibly strengthens my claim that the correct alternative here is [B]:
Putin is hardly popular among Germans, but [then] neither is the prospect of a scrap with Russia on Ukraine’s behalf.