I can see how people can be fooled into getting one of these things instead of a proper bike. I almost did the same. For me it was largely ignorance. I was returning to cycling having last owned a bike 35-odd years previous when I was a kid. I started looking in the normal places (Halfrauds etc.). I had fallen into the full-sus camp as that is what I saw was most popular. Luckily for me, a more informed cycle mad work collegue offered me some advice. Get something decent he said else you will not enjoy riding it and it could put you off riding. He gave me a list of reputable makes and from what I wanted it for, he suggseted that a hybrid would be a better fit than a full-sus. Plus to get a decent quality full-sus it would be a lot more money. Anyway, I did a bit of searching. I was initally shocked at the prices. They were all round the £400-£500 range for a decent hybrid. I had it in my head to pay £200 tops as that is what I had in my mind was a good price for a bike. Afterall its only a bike isn't it?; It isn't that complex (I thought). In the end I went for a Trek 7.3FX at £425. I still have it and despite doing many miles on it, it is still original and the only parts I have changed are chains. So I was one of the lucky ones who got some good advice and was saved - many are not.
On the flip side. a relation recently wanted a bike to get round town on. She looked online and in catalogs. She asked me about a bike she had seen in a catalog of some sort. It was the ubiquitous budget double-bouncer at the sum of £149. My heart sank. I told her to give me the money and I'll get her a much better used bike for that money. She said why get a used bike when she could get a shiney new one for the same money? I tried to explain, but she just didn't get it. Anyway the "thing" arrived and I was asked to put it together. The front wheel was so far out of true that it would never have cleared the brakes so I didn't even bother to attempt the build. She sent it back. Good I thought, she's had a change of heart. Nope, so just got a replacement. Again it was my job to build it. This time the wheels were not that bad. Ten minutes with a spoke key got them quite true (how long they'd stay like that was anyone's guess). It had plastic brake levers. The seat was in instrument of torture. It weighed at lot. The rear gears would not go all the way into top, and would also over travel at the bottom and the chain would fall off. Index screws were adjusted and this was fixed. However, despite a lot of effort, I just could not get the indexing to work anyway near reliably. However, when I was finshed, it was at least safe to ride. I lasted less than a year, depsite light used, before the the BB fell to bits. The cost to fix that and other issues that had developed, made it uneconomical to repair, so it became another destined to landfill.