There's an inherent chance that some will misuse the system like you state, but that's no reason to discount the entire system anymore than saying that because one nut job kills someone with a gun we need do something about guns.
I'd just like more corroboration before things like this happen. We are a country based on having and protecting civil liberties, however trivial they may seem. It just seems morally objectionable, to me, to allow seedy elements of society (oftentimes felons) so much power to wield influence.
So in my example, get a tip? Okay, great. Carry out surveillance. Sit on the house. Look for what would align with drug movement. Don't get the warrant that day, fail to get a proper profile of the family - being completely unaware that children even lived there, and bring an actual SWAT team in.
I know none of my ideas/thoughts will ever amount to any actual change. It's just discouraging to me that, should some girl I dumped 3 years ago decide she doesn't want me to get married to my fiance, she could just claim that I raped her or something. Or that I was a drug dealer. Will I go to prison absent of evidence? No. Will my life, likely, be significantly impacted if they only go off of her word? Absolutely.
It is what it is. An imperfect system. I'm just thinking out loud.