Windows For the Soul - Photography

Helios 44M 58mm f/2 M42: is a 20€ lens a waste of money?

Is spending 20€ on an old lens a waste of money? This is a question that I had to consider before buying a crappy old Helios 44M 58mm f/2 M42 (8 Blade version) and one that I still struggle to answer. Fortunately, 20€ is not worth much thought and it does not demand a proper and definitive answer. I took some time off for a couple of afternoons in the countryside, hoping to find some late summer butterflies. I carried my usual gear but I decided to also toss my extension tubes and my old Helios 44M 58mm in my backpack. There were hardly any butterflies to be seen but dragonflies and damselflies did not miss the call, so to speak.
This lens is said to afford exquisite swirling backgrounds and several examples can be found on Flickr. This alone would make those 20€ a ridiculous bargain but my experience, most likely due to my clumsiness, can only confirm that results with this lens are rather a hit-and-miss affair, and, even with a lot of effort and thoughtful management of settings, distance to subject, distance from subject to background and light conditions, I would dare say that this lens is, to be gentle, extremely unpredictable. Too often I am left with the feeling that a pleasing result is rather a matter of luck. Be that as it may, the fact is that, if I put in an extra effort, I sometimes come away with a few photos that I actually like. However, I can't help thinking that it is a lack of image quality that produces those results.
In the first three of photos below, I coupled the Helios 44M 58mm f/2 M42 with a Nikon D600.
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Nikon D600, Helios 44M 58mm f/2 M42 (8 Blade version), ISO 400, 1/160, f/2.

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Nikon D600, Helios 44M 58mm f/2 M42 (8 Blade version), ISO 640, 1/160, f/2.

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Nikon D600, Helios 44M 58mm f/2 M42 (8 Blade version), ISO 640, 1/160, f/2.

Experimenting with this lens in the macro photography genre, I coupled it with an extension tube. However, the blurred background was by no means extraordinary and the best I could get was the shot below, taking advantage of the dark background to hide the quite hideous out of focus background and the rather large maximum aperture to obtain a paper thin depth of field, highlighting the creature's eyes. However, as it is usual in my case, manually focusing was a real PITA even using the live view mode on the D600. I think I ought to pay a visit to my ophthalmologist one of these days.

Coming back to my initial question, is this 20€ old lens a waste of money? I am yet to figure it out…
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Nikon D600, Helios 44M 58mm f/2 M42 (8 Blade version), ISO 640, 1/160, f/2.