What do the locals think of this stretch? Aside from a few respectable patches, this section of Yonge seems generally seedy and decrepit. It's a shame, as it could be so much more. I'd like to see it refreshed and cleaned up, get rid of condom shacks, jewelry/pawn shops, and all those scuzzy looking stores that sell nothing but cheap junk. Maybe these add character, I don't know, but when friends and family visit we always walk south from Bloor down University or Bay, through Queens Park, etc, as the Yonge sidewalks on that stretch are often full of vomit and spit and mentally-ill people. Not the best face forward when trying to impress visitors.
The negative things you mention don't really bother me as much as you or many people that have discussed this issue earlier in this thread.
I don't mind seediness or "decrepitness" (sometimes described as grittiness). Although, I've lived near there in the past and I didn't find it filled with vomit like you describe, or as bad as you seem to perceive it.
On the other hand, I value liveliness, vibrancy, high pedestrian activity and things like short storefronts, so I prefer that stretch of Yonge over say a clean but sterile street full of large banks or big stores. I also prefer it over a clean & new but suburban environment.
It also probably wouldn't be the place I would take visitors however. I usually take people to places like Kensington Market, Distillery District, Little Italy etc.
I think there are a lot of different cultural values in Toronto and they tend to end up liking or disliking different things. For example, I've noticed that some groups of people tend to only prefer newer large suburban houses and consider anything older than 20 years to be too old. On the other hand, I consider older houses to generally have more charm and character, even if they need more work, and I prefer older neighbourhoods.
Similarly, I don't really find Yonge to be as offensive as others, because I guess I value different things. I grew up in North York, so I've always found the vibrancy and urban-ness (for a lack of a better term) of downtown Yonge to be exciting and a fun place to be.
Having said all that, it will gentrify, like Queen West has, and Yorkville has before that, and condos will likely replace all of the buildings many find unappealing, so regardless of our opinions it will inevitably lose most of its grittiness/character/decrepitness/dirtiness.