Sure no, even demo live tests should not be a deciding point to buy an EA, only live real accounts will tell the truth, as on demo you get your orders filled no matter what and this is not the case in live trading.( see this post )
I guess some has already experienced testing an EA for a couple of months and when using it on a live account, it does not perform the same.
Anyhow for the record there are many Holy Grails on forex-tsd.com, the only problem EAs should not be left to trade by it self, people should modify the setting from day to day from week to week based on the market conditions.
In simple words: analyze the market and change the setting on your favorite EA on that week or that day to sell only or buy only, and don’t let it trade by it self, and for sure don't buy an EA based on backtests or even demo live tests.
This is how I set the EA to
trade