(1) The seller of the expert advisor should also be developer and there should be a working/valid email address and other contact information. The developer should also be able to provide information and answers to your questions without hesitation.
(2) There should be no hype, period. Many offers on the net are just full of hyped up advertisement and sales talk. You need to look for proof such as testimonials and honest reviews from actual traders.
(3) It is best to look for forward testing statements since their results are better and more useful to your trading. What the forward testing does is that it shows you how the system will trade and respond in various live market conditions. Forward testing should be the primary factor to help you decide when it's time to purchase and it should be able to determine if the advisor is profitable and reliable.
(4) There should be continuous after sales support. This is important because the forex market itself evolves continuously and the expert advisor should be able to adjust in unison to adapt on-going market conditions. Regular upgrades are essential so that the software is always up-to-date with the market in order to stay profitable.
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