I have pretty printed and removed the <?xml version="1.0"?>
from all success / failure examples below.
Success:
<ApproveAssignmentResponse>
<OperationRequest>
<RequestId>bc6cf077-5d66-4f74-f943-14ea8a57b95b</RequestId>
</OperationRequest>
<ApproveAssignmentResult>
<Request><IsValid>True</IsValid></Request>
</ApproveAssignmentResult>
</ApproveAssignmentResponse>
Failure:
<ApproveAssignmentResponse>
<OperationRequest>
<RequestId>41447390-1b93-bc99-603f-c380b31306b3</RequestId>
</OperationRequest>
<ApproveAssignmentResult>
<Request>
<IsValid>False</IsValid>
<Errors>
<Error>
<Code>
AWS.MechanicalTurk.InvalidAssignmentState
</Code>
<Message>
This operation can be called with a status of: Submitted (1432965840161)
</Message>
<Data>
<Key>ExpectedStates</Key>
<Value>Submitted</Value>
</Data>
<Data>
<Key>CurrentState</Key>
<Value>Approved</Value>
</Data>
<Data>
<Key>ExpectedStates</Key>
<Value>Submitted</Value>
</Data>
</Error>
</Errors>
</Request>
</ApproveAssignmentResult>
</ApproveAssignmentResponse>
Success:
<CreateHITResponse>
<OperationRequest>
<RequestId>3f92bc3d-07f8-40db-2e60-f8b21bf5f2f0</RequestId>
</OperationRequest>
<HIT>
<Request><IsValid>True</IsValid></Request>
<HITId>3WHORRWKX9ZSGPJ91RCSHNS30HQYV7</HITId>
<HITTypeId>3J7M3LFX1852SDL4672AKD88EC7JW1</HITTypeId>
</HIT>
</CreateHITResponse>
Success:
<CreateQualificationTypeResponse>
<OperationRequest>
<RequestId>5103d10b-0aad-e50a-a6a8-b18124be8d11</RequestId>
</OperationRequest>
<QualificationType>
<Request><IsValid>True</IsValid></Request>
<QualificationTypeId>38Q5TG7DC0WTHBC9RKV0Z4LN8YAQ40</QualificationTypeId>
<CreationTime>2015-07-09T00:39:15Z</CreationTime>
<Name>Test qualification 1</Name>
<Description>My first qualification type (temporary)</Description>
<Keywords>test,autogranted</Keywords>
<QualificationTypeStatus>Active</QualificationTypeStatus>
<RetryDelayInSeconds>1800</RetryDelayInSeconds>
<AutoGranted>1</AutoGranted>
<AutoGrantedValue>1</AutoGrantedValue>
</QualificationType>
</CreateQualificationTypeResponse>
Failure:
<CreateQualificationTypeResponse>
<OperationRequest>
<RequestId>a409ccd6-8623-49cd-6868-1888fd73e6ce</RequestId>
</OperationRequest>
<QualificationType>
<Request>
<IsValid>False</IsValid>
<Errors>
<Error>
<Code>AWS.MechanicalTurk.QualificationTypeAlreadyExists</Code>
<Message>
You have already created a QualificationType with this name. A QualificationType's name must be unique among all of the QualificationTypes created by the same user. (1436761963958)
</Message>
<Data>
<Key>QualificationTypeId</Key>
<Value>38Q5TG7DC0WTHBC9RKV0Z4LN8YAQ40</Value>
</Data>
<Data>
<Key>QualificationTypeId</Key>
<Value>38Q5TG7DC0WTHBC9RKV0Z4LN8YAQ40</Value>
</Data>
</Error>
</Errors>
</Request>
</QualificationType>
</CreateQualificationTypeResponse>
Success:
<DisposeQualificationTypeResponse>
<OperationRequest>
<RequestId>c973f145-ca3b-7417-39a9-b28154b42f7e</RequestId>
</OperationRequest>
<DisposeQualificationTypeResult>
<Request>
<IsValid>True</IsValid>
</Request>
</DisposeQualificationTypeResult>
</DisposeQualificationTypeResponse>
Failure:
<DisposeQualificationTypeResponse>
<OperationRequest>
<RequestId>4debb56c-294a-2a33-a3e1-fadb9fd3d651</RequestId>
</OperationRequest>
<DisposeQualificationTypeResult>
<Request>
<IsValid>False</IsValid>
<Errors>
<Error>
<Code>AWS.MechanicalTurk.InvalidQualificationTypeState</Code>
<Message>
This operation can be called with a status of: Active,Inactive (1433596333756)
</Message>
<Data>
<Key>QualificationTypeId</Key>
<Value>3ISAMW410AS3H0PXAB30C72RWEHCQJ</Value>
</Data>
<Data>
<Key>CurrentState</Key>
<Value>Disposing</Value>
</Data>
<Data>
<Key>ExpectedStates</Key>
<Value>Active,Inactive</Value>
</Data>
<Data>
<Key>ExpectedStates</Key>
<Value>Active,Inactive</Value>
</Data>
<Data>
<Key>QualificationTypeId</Key>
<Value>3ISAMW410AS3H0PXAB30C72RWEHCQJ</Value>
</Data>
</Error>
</Errors>
</Request>
</DisposeQualificationTypeResult>
</DisposeQualificationTypeResponse>
Success:
<GetAccountBalanceResponse>
<OperationRequest>
<RequestId>3dfd11c8-244b-bc5b-f788-701b26b114a3</RequestId>
</OperationRequest>
<GetAccountBalanceResult>
<Request><IsValid>True</IsValid></Request>
<AvailableBalance>
<Amount>356.490</Amount>
<CurrencyCode>USD</CurrencyCode>
<FormattedPrice>$356.49</FormattedPrice>
</AvailableBalance>
</GetAccountBalanceResult>
</GetAccountBalanceResponse>
Success:
<GetQualificationsForQualificationTypeResponse>
<OperationRequest>
<RequestId>685fb2c4-6058-e704-c9fb-4fda448d34dc</RequestId>
</OperationRequest>
<GetQualificationsForQualificationTypeResult>
<Request><IsValid>True</IsValid></Request>
<NumResults>20</NumResults>
<TotalNumResults>20</TotalNumResults>
<PageNumber>1</PageNumber>
<Qualification>
<QualificationTypeId>369ZZFP90OYIK697277WBGQQMK754X</QualificationTypeId>
<SubjectId>AP3WTN0J7ZAUNG</SubjectId>
<GrantTime>2015-07-08T16:47:02.000-07:00</GrantTime>
<IntegerValue>1</IntegerValue>
<Status>Granted</Status>
</Qualification>
<Qualification>
<QualificationTypeId>369ZZFP90OYIK697277WBGQQMK754X</QualificationTypeId>
<SubjectId>AFZF7E6VRDTXUN</SubjectId>
<GrantTime>2015-07-08T16:51:50.000-07:00</GrantTime>
<IntegerValue>1</IntegerValue>
<Status>Granted</Status>
</Qualification>
</GetQualificationsForQualificationTypeResult>
</GetQualificationsForQualificationTypeResponse>