Scan PUP isnt turned on in any of the scan options why?

[mary sladdin]

My PC was working VERY slow at start up and I was hastling my server provider...it worked out I had 75 things opening up at start up and a 2 pup virusus on my C drive_ avast is always on except a few times I have had to turn it off to allow functions to activate my PC. My big question is-even if I scan PC with any of the optionsPUP is not on unless I select it, this dosent make sense? as why would I be doing a scan if i wasnt looking for PUP's? anyway my point is that this means I have never had PUP selected withANY scan the computer makes at start up or even when I select a scan option and ask it to scan!? this is confusing, as what is the antivirus actually doing then if its not looking for PUPs? and why dosent it specify that I MUST select scan PUp OR IT WONT BE SCANNING THEM_IT REALLY SEEMS STUPID?
dOES ANYONE HAVE ANY ADVICE OR SUGGESTIONS TO HELP ME CLARIFY THIS(SORRY HAD CAPS LOCK ON)

[Gargamel360]

Because Avast! makes a product for everybody.  And not everybody knows what a PUP detection means.  

This part of the user base is going to think PUP means virus/infection.  And PUP delivers detection on a number of legitimate applications that can be used both for good or bad.  So if PUP was on by default, and it flagged something legitimate, a less informed user will act hostile toward it by default.  Then they go to the vendor of the application that got detected, and the say "you gave me a virus", then the vendor says "this is a FP" (even though its not), leaving the user lost in the middle, and both the makers of the detected tool and Avast! with a lesser reputation.