I think the first hurdle anyone faces with cryptocurrencies is that they are money, in every sense of the word. Bitcoin and Dash function like fiat currency, just without a nation-state backing their value.
As for the association of crypto with criminality, one must first spend some time looking at the teams behind each currency. If all the folks currently rushing to build the next big crypto all turn out to be crooks, then the global economic system is in far more trouble than we think it is.
Of course, there is always the other possibility to consider: That since cryptocurrencies carry actual, tradeable monetary value, criminals are bound to find them attractive, because greedy people like money, not paper.
So I would then say, that criminals are criminals whether they use crypto or cash. If all criminals used crypto, that would still not be enough evidence to convince a court that everyone who uses crypto is a criminal.
Hope that made sense
@your-nomad-soul There's a discussion point there, regarding whether cryptocurrencies are in fact money. One arguable factor is that money includes a "Store of Value" factor. For traditional precious metals an ounce of silver represented something like 20 "man hours" to extract and purify it. For mining operations like Bitcoin, Litecoin, etc where mining is required (like legit ore being pulled from the ground) I agree - it costs something like $1000 in power consumption and man hours. What about other altcoins where no mining is required? Like Steem for instance. Is that actually money? I'm not sure.