Read "Life as no one knows it"
It makes the most science based argument on how to detect alien life... and it doesn't involve looking for life with microscopes... it is more scientific than that, it involves looking for molecular traces that are unlikely to occur outside the product of evolution. It makes a brilliant argument based on complexity and information theory, that doesn't rely on biases we have from only knowing Earth life... scientists aren't as greedy and stupid as you seem to assume.