I dont believe all alts are a scam.
I'm not naive to think that there arnt any.
The biggest thing that needs to be looked at is real world use case for the coin. does it have a purpose?
alot of these coins that talk about ROI rather than actually have a purpose, i simply look as scam coins so try avoid.
If i am wrong on the occasion i take it and move on with life.
Too many masternode coins that all talk about ROI's rather than use.