This can indicate fraud, duress, or undue influence.
In contracts, "consideration" is the things of value each side gives up in an exchange. So if one side gives $1 for a cup of coffee, that might be ok. Now, consider if the contract was to sell your entire house for $1! That would be a shockingly inadequate exchange because even the cheapest home is worth way more than $1.
In that case, the judge might look at why someone would be willing to give up so much for so little. Were they falsely told there home was worth nothing or maybe told that they would get $1 upfront and more later? That would be fraud. Were they told to sign the contract with a gun pointed at their head? That is an example of duress. Finally, did the person helping them with the contract have undue influence? If your boss, parent, or favorite celebrity advises you to do something that you don't want to do, but you worry about what they will thing if you don't, then you were a victim of their undue influence.
