Technically you can actually as there's a "grey" area in the testing procedure. For example the 4:1 testosterone to epitestosterone ratio....some jurisdictions allow a 6:1 ratio. Linford Christie fell into the "grey" area many times for stimulant tests. If you take those as examples you really can pass with flying colours.
Wlad never fail. Never tested positiv. He fought in the Bundesliga and was tested in training too (german standards.)