Can I ask what is cold rent here, does that does not include utilities or similar? Also how does the second illegal thing work, is that subletting basically?

> Also how does the second illegal thing work, is that subletting basically?

I'm not sure if this is what gp meant, but:

In some cases the current tenant (who is looking to move out) offers you the landlord's contact details if you agree to buy their kitchen for way too much money. This works because for a landlord looking for new tenants is a lot of hassle so they're likely to take you if you contact them.

Can't answer the second question. As for the first one: in Germany, you pay rent plus an advance for certain utilities (heating, cold and hot water, trash collection, general maintenance of common areas etc.). The rent without the advance is commonly called "cold" rent (Kaltmiete). The advance is variable based on actual usage. So the common way to compare rents is by excluding that.