You look at the market depth to get a feel where the market is moving. And spoofing modifies the sizes at certain price levels.
A market is supposed to enable trades that benefit both sides, because otherwise who would dare use it? Selling means I need money and I'd rather have the share price now, buying means you have money and you'd rather have the income in the future, and it doesn't have to be a regrettable mistake for either of us.
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