Buying a property with existing tenants

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I'm interested to purchase auction houses, but it concerns me when I read "Buyer Assumes Responsibility of Occupancy".

I do believe buying a house from an auction is considered as foreclosure. Is it absolutely legal to get the tenants out of the house after the purchase (assuming these are not the tenants I wish to keep)? (Please don't provide any information on I should interview the tenants first as I'm trying to find out the worst thing possible for buying a property with tenants in it that I do not want).