I dont know if its a lately thing, meaning I dont think thiers a lot of bad batches of gear everyone or just more irresponsible people, I think its always happened you probalby just notice it more because you hear about it a lot easier when connecting to people through the net.
I got my first and hopeflly last last year from what I beleive is from injecting way too much enath in the same shoudler or too often. Every abcess Ive heard about thiers a story behind. most recently it seems mostly from home brew gear. Other then that just dont re use needles, get into practice of wipping your site with alcohol pad along with the septum, and if your going to shoot air into your bottles to create pressure, draw back on syringe with the it still capped. Just some basic obvious stuff, but its probably rushing through the basic stuff thats responsible for most abcesses.