An EA advert leads with the profit percentage and a smooth curve going up. That is the most pliable part of a report: you can get it by fitting parameters to history. Here is what I look at when I receive someone else's tester report or check my own.
Drawdown matters more than profit. Maximum equity drawdown (not balance drawdown) shows how much you will have to sit through for the result. 130% profit with a 60% drawdown and 40% profit with an 8% drawdown are two different products. Look at the profit to drawdown ratio, and at whether you could live with that drawdown on your own deposit.
Number of trades and their distribution. Twenty trades a year is statistics about nothing. You want a sample of at least hundreds of trades, and profit that builds up steadily, not from two or three lucky entries. Check what share of the result comes from the three best trades.
Test conditions. Period, tick quality (real ticks versus "open prices only"), spread, commission, slippage. A zero-spread test for a grid or scalping EA almost always overstates the result.
Robustness. Shift a key parameter by 10-20% and run a different period. If the result falls apart, it is curve fitting. A working system loses a little, not everything.
Extra caution with grids and averaging: they can draw a smooth curve for years, then one prolonged move against the position eats the deposit. Look at maximum floating drawdown and maximum position size, not only closed trades.
And above all: a backtest is a hypothesis, not a forecast. No report guarantees future performance. A sensible minimum: a demo account or a small size first, and only then scale up.
For the EAs in the shop I state the symbol, period and settings the result was obtained with, so it can be reproduced: kovalev.trade/shop
Got a tester report or a strategy to check: kovalev.trade/development
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