All sources are politically biased. Some are just more honest about it.

Just making a generic statement like that without qualifying it serves only to excuse that one source. Are the government of China's comments on Tibet equal in weight to Amnesty International? No. Is the Heritage Fund pushing an agenda equal in trustworthiness to an academic international ranking? Probably not.

However, academic studies from two accredited institutions that don't have a particular ax to grind are probably equally credible.

"Heritage is biased" is the unqualified generic statement, and it serves only to reinforce the dangerous idea that some organizations are unbiased and can be blindly trusted.

Of course Heritage is biased. But their Index has a well defined methodology and provides the data that informs the final score for each country; it can stand on its own, and should be criticized as such.

Right. See the recent news about Facebook's curation 'algorithm'.