In Checklist of Suspicious Features, Jacqueline A. Joseph, Certified Document Examiner and handwriting expert witness writes:
If you have a suspicious document or handwriting or typewriting, these clues should alert you to the need for a document examiner:
Only copies are available, and they are of unusually poor quality.
The handwriting appears to be of multiple styles or of a style the alleged maker may not have used, such as printscript by an American educated before 1940.
The handwriting has the same pressure throughout or has blunt beginnings and endings. This may indicate the writing was deliberately drawn to imitate a model.
For more, see http://www.jjhandwriting.com/