How much of a discount to ARV do foreclosures usually sell for at Colorado Sheriff's sales?

I'd say it is 80%-90% sales and hype and 10% content.

Not sure what a “subject-to” home sale entails?

disclosure laws vary by state and if a private sale or thru Realtors The buyer is generally supposed to verify information

“Thankfully, Fannie Mae, Freddie Mac and the Federal Housing Administration have all announced temporary moratoria on evictions and foreclosure sales in Harvey-related disaster areas,” Graboske said.

Dead space in attics, basements, breezeways and covered parking can be a boon to the bottom line on rents AND future sales.  

Just from looking online I've noticed there's a lot for sale but also what would be good areas to invest in??

I may have found foreclosures as "Notice of Substitute Trustee Sale"?

@Achi Adamit, if you had the intent to hold that lot while deciding how to ultimately handle it and didn't do something like have it listed for sale the entire time you should be able to do a 1031.  

In all likelihood there are no more redemption rights and even a void tax sale has been cured with 3 years of adverse possession after the tax deed date.