Can you elaborate on number 1? For instance Numbeo summarizes:
Cost of living in Barcelona is 35.00% lower than in ____
You would figure it is really only 25% cheaper? Are you comparing just some itemized costs you incur on a business trip or are you actually moving to these places as a resident and making that observation? I ask because a 10% margin of error hasn't been my experience.
1. Numbeo: add a 10% "against" you to be on the safe side
2. Salary Calculators: whichever "salary calculator" you are using, add a 10% "against" you (taxes-taxes-taxes)
3. To whatever utilities you are calculating, add another 10% "against" you to for "building administration", "council/city tax".
Do 1-2-3 and you will not have any surprised to your cost-of-living calculations.