"In all billing matter I object to the use of the words of Hocum and Fakery. They are too vulgar."
In the Akron ad we see both offending words featured prominently, exactly the kind of "vulgar" advertising Houdini wished to avoid. This could even be the ad that motivated him to add this stipulation, although I have seen the words used elsewhere at this time. You'll also notice the bottom of the ad containing the lecture details is a mismatch with the top of the ad, which is curious. By the day of the lecture, the advertising had been tamed more to Houdini's liking.
So why didn't Houdini like the words hocum (hokum) and fakery? I think it's simply a matter of him wanting his lectures to perceived as serious presentations and not magic or spook show entertainments. Another stipulation for this second tour was that he would not perform his Milk Can escape as he had during his first tour. Of course, this perception didn't aways come across, as was most acutely demonstrated during the Chattanooga debacle.
It's interesting to note that Milbourne Christopher makes reference to this contract stipulation on page 200 of Houdini The Untold Story. However, the book contains a misprint, saying Houdini objected to the use of the words fakery and hocas. This was never corrected in any edition, and I'm sure more than a few folks were puzzled as to why Houdini would object to the word "hocas." This is a good example of why going back to original source material is so important.
I for one like the word hokum, and it has gone on to be associated with Houdini. In fact, Hokum was the original proposed name for Penn & Teller's skeptical television series Bullshit. Now there's a word Houdini would have objected to!