Tether might be a possible scam. Rumors about Tether are caused by the failure to release a profesional audit of their books. Tether claims to cover hundreds millions of Tethers to be backed by an equal amount of USD.
General pump and dump schemes, especially for penny tokens where marketing pushes the price up, only to be abonded at the higher price by early pump buyers.
- Bitcoin Gold
Bitcoin Phishing Scam (note the dash in the domain) which bagged $50 Million Over 3 Years