The switches I use are not from Asia Engineer (the amp and volt meters are however). I have not had issues with my switches. They're an all-metal body and look like this:
I tried a few different types of switches before settling on these ones with metal bodies. Some of the all plastic ones I tried simply did not seem like they would last - even the contact blocks used really cheap parts and did not always switch properly.
I would make sure that the contactors (contact blocks) on yours are not loose. There's a screw to hold them in place.
Allen Bradley and other companies most certainly do make better switches. It's immediately obvious if you have both in your hand and use them. The actioning is considerably better. I seriously considered using all AB on my setup but paying $50+ per switch instead of $3-4 was more than I could swallow.
The ones I ended up with seemed the be best bang for the buck for me.
You may have also gotten a bad batch too. You never know. If you can't figure it out, contact the seller.