An Engineer or A Doctor?

An Engineer was unemployed for long time. He could not find a job
so he opened a medical clinic and puts a sign up outside: "Get your
treatment for $500, if not treated get
back $1,000."

One Doctor thinks this is a good opportunity to earn $1,000 and goes
to his clinic.

Doctor: "I have lost taste in my mouth."

Engineer: "Nurse, please bring medicine from box 22 and put 3 drops
in the patient's mouth."

Doctor: "This is Gasoline!"

Engineer: "Congratulations! You've got your taste back. That will be
$500."

The Doctor gets annoyed and goes back after a couple of days later
to recover his money.

Doctor: "I have lost my memory, I cannot remember anything."

Engineer: "Nurse, please bring medicine from box 22 and put 3 drops
in the patient's mouth."

Doctor: "But that is Gasoline!"

Engineer: "Congratulations! You've got your memory back. That will
be $500."

The Doctor leaves angrily and comes back after several more days.

Doctor: "My eyesight has become weak."

Engineer: "Well, I don't have any medicine for this. Take
this $1,000."

Doctor: "But this is $500..."

Engineer: "Congratulations! You got your vision back!

That will be $500."