Just pulling your chain.  SD has had some aggressive LE activity lately.  Happens every few years and will die down when they reach a diminishing return.  Some touring girls are skipping SD right now and some of the locals are stepping up their screening for new clients.

LE just shut down their local escort website that was up for 10 years so I'm sure that has something to do with it.
Like me, many providers, will come specifically just to see you if they are relatively close by. I'm in the OC, and I go often to San Diego for clients for incalls and outcalls although I may not have a tour posted. You can just pm the gal you had in mind, and you'd be surprised how many of us would love to see you

It has happened to me a few times over the years and I've heard similar comments. San Diego is a funny market, whether it's for hobbying or RL. Probably a combination of the 3 - SD is a tough town to tour if you don't have an established base, seasonal, and bad luck.  

I had no involvement with that site that was taken down, so can't say what affect it had on the psyche of hobbyists to go out and play.

It's really hard for those of us who are from the area, and have regulars- to comment.  I do often find that some ladies don't really understand the concept of "marketing" too well, and then can't understand why they don't have business.  But, as we live here- we can't compare it to other areas.  I have a marketing background and understand the need to run ads months before I travel, and consistently keep the ads updated and fresh.  Many just don't get it- then blame it on the location.......

Touring?

Sorry to say, perhaps just bad luck.  
Indeed, the proximity to TJ, definitely hinders quality or quantity if you will.  
And finally, we don't really have "seasonal" fluctuations, except perhaps,
for Thanksgiving through New Years.
Better Luck Coming Your Way,
Angelina Jones