Ok, so let's start with sideloading.
By the way you asked, you guessed correctly that depending on what's being sideloaded, I am WAY not ok with it.
If you mean to get paid apps for free, as most people new to rooting do, just don't do it.
I could go into morality because I'm a software dev and I don't want it done to me.
I could go into the law because it's illegal copyright infringement.
I could go into logic and explain that it's the number one malware infection vector, and everyone who has argued with me on that has eventually come back with a mysteriously screwed up phone despite, "Hahaha I got it from my friend and it hasn't hurt him!" - or - "Hahaha I can patch it myself so screw you!"
But the reality is just being a little bit of a thief is exactly like being a little bit pregnant. You are or you aren't and whether you believe it or not and whether it's logical or not, doing it affects your karma and it's never ok.
If you can't afford an app, you don't need it and there's probably a free one that's close enough.
But here is where it is ok to sideload and it goes into why I had you install SuperSU - an ad blocker.
Not because ad blocking is bad or good - but because ad blocking is done with a blacklist and that blacklist also blocks malware sites.
http://forum.xda-developers.com/showthread.php?t=2190753
It uses zero battery to use that, because of how it works.
There are no names on the internet, just addresses - google.com is there for humans, a domain name server (DNS) action happens to translate that into the address.
Before that happens, whatever wants it looks on the phone instead of DNS on the network to see if it can save time. The ad blocker is just a list of names that say the address is a black hole so nothing happens.
But the only way to update that list is with root.
With rare exceptions like that - or other good tweaks from XDA - don't sideload.
