Sorry if this all sounds a little harsh, but you posted in a critique section, explicitly asking for critique on the images. However, you've come to the right place for help and feedback if you really want to improve the quality of your work - there are lots of really talented shooters on here - including people who make a living producing "product shots" - so if you take notice of them, things should certainly improve...
On the contrary - I enjoy harsh feedback, as it says a lot more than, uhm, 'soft' feedback; I really appreciate the long and very detailed message. Lots to think about, to be honest.
Anyway. I'm going to comment on some of your points now.
What you said about lighting... To be honest, I was constantly annoyed when shooting, wondering whether my settings are bad or my lighting is bad or... What is happening. My lighting consists of a single fluorescent 4000K desk lamp peculiarly mounted on a... Weird contraption. So yea, it is definitely not good, not at all. Other than that, there's the flash, but it's really difficult to get decent results with a flash (I'm using Nikon D3200), for me at least.
So now we move onto window lighting... Which is unfortunately problematic. Where I spend most of my time is a dark room, there are no windows here. The room with windows has very little space and since the stuff there isn't mine, I can't throw it out, so there is no way I can photograph there. Moving on to proper lamps and something more decent than glued-together pieces of paper, to be honest I don't want to spend any money on things that I wouldn't be able to easily take with me in case I'd need to move to another country. As you may have heard on the news, Eastern Europe is becoming increasingly more fearful of Russia (rightly so, it seems), so I may need to pack up and get out within hours at some point. I don't have much stuff, but I wouldn't be able to take big lamps or something like that, and since I don't have much money in the first place (had to save for years for this camera), it'd be stupid for me to spend money on such things.
Anyway, having said that, I'll refrain from attempting such shots, as it appears that I won't be able to achieve the needed result, and I can't think of any other proper way to achieve them, then... I do, however, appreciate the comments and I'll remember them for when I'll be able to proceed with them.
As for your comments on not trying to be artistic for Ebay, I have shots for Ebay that aren't artistic, however I saw an interesting side that I thought might look good and thought I'd snap that picture to post here. So these shots probably will never reach Ebay, as I have proper ones that just show the features for it.
As for cleaning stuff, yes, that is an excellent point. My excuse(?) for not cleaning is that I don't expect to sell anything and that I will set cheap prices because I just want to get rid of as many things as possible to make as much money as possible in case I would have to move away due to Russia. Since I honestly don't expect to sell anything because things I have are generally in a pretty poor condition (so people would buy them to restore them or to use them for parts, etc.) or when it comes to tech, they're simply old... Well, having said that and my rather valid lack of expectation for anything to sell, cleaning them would be a waste of time, not to mention that the buyer would have to clean them himself anyway as they'd need to restore them into a usable condition.
In other words, I'm just taking a chance with Ebay for the most part by trying to sell things that are pretty much useless. Wish we had garage sales here, that'd be absolutely perfect for such crap.
Thanks again for the long and descriptive post;
a lot of useful and helpful information. I'll stick to pictures I'll take outside from now on. Though I'm trying to do things inside now as I need to at least somewhat get ready to get out of this country in case something more serious than Russian jets flying around the borders and Russian propaganda happens.