Lack of transparency — the real heavy weapon (§ 6(3) KSchG)
A clause must be clear and comprehensible and must not obscure the legal position. This is precisely where most representative actions start — and it regularly hits entirely ordinary standard clauses: for example, when it remains unclear when the contract is actually concluded, when reference is made to "the stated reasons" without naming them, when cancellation or processing periods are vaguely worded, or when the customer is left to work out the permissible scope of a clause for themselves.