My washing machine plug causes the washer to stick out about 4 inches too far because the plug is not 90 degrees. Can I safely plug the washer into a heavy duty power strip with a 90 degree plug?
Might also be an option to change the power cord on the washing machine. Many larger machines like that are designed for fairly easy cord swap. Take a look at the termination type on the existing cord; then shop for appliance cords that have the bend you require. McMaster-Carr is a great source for finding specialized and specific things like that.
Most, if not all, owner's manuals will say not to use an extension cord as a safety precaution. However, you should be able to use a right-angle power adapter to solve your problem. Because of their very short length, they do not pose any safety problems. Be sure to get a quality UL rated unit with a rating of at least 15 amps. They are available at any home center.