Fads basically occur when a small group of respected people go out on a bit of a ledge to support something (a team, a stance, a piece of clothing) and in a very short amount of time, that thing, whatever it is becomes immensely popular, not necessarily because the clothing is so ergonomical or that the stance makes sense, or that the team is really any good. But they follow it because as humans, we want to be part of a mass movement. We want to be accepted by mainstream audiences.
This is sort of what happened with TFC, except that (warning: oxymoron) the fad lasted for at least 3 years and will continue if the team is good because they were able to convert people in it for the wrong reasons (local party scene!) into actual soccer fans and specifically TFC fans. And like I covered before, the stadium is so small, it will always either be sold out, or look sold out. It would take overpriced seats and a few years of a bad team to make it less trendy.
Anyways, part of this mass movement creation is the overall visibility that the team has in its city, or wherever the largest population of people in the team's region resides. Teams whose cities don't care about them are hidden-nobody is wearing merchandise, there are no billboards, or advertising. They remain anonymous in a city thinking about other things. You can tell by walking in a city's downtown what teams the people are supporting just by being observant. I went to Chicago in 2005, didn't see a single Blackhawks hat, jersey, no billboards, no newspaper coverage. They may as well have not existed. But if you walk through Boston, everybody you see either has a Pats, Sox, or Celtics shirt. You know those teams have outpouring of support without even going to a game. It's part of their mainstream culture.
That's an ideal situation. But sometimes you can't have that advertising support from fans wearing merchandise. Instead you have to brand the logo around the city through partnership endeavours and regular advertising, and that's fine too. Locate highest areas of people traffic, and invade their senses with your logo and slogan. "Wamco is the #1 fan of the Blue County Road Hounds". Include players--put a face to the organization and pique their interest. People don't know what they like until they see other people liking it. This at the very leasts gives an impression of presence, that's valuable. Have street vendors display your teams flag--pay them for it! Strike deals for local bars to broadcast your team's games with sound for patrons attending. People naturally gravitate to whatever the TV is on...it makes for good conversation. These things are crucial. If I'm new to the area and I walk in a bar and people are watching whatever game is on tv, to me, that looks like they're interested in it. And I want to watch what other people here are interested in. This goes especially for places with high immigration--you have the opportunity to shape these people because they want to belong in YOUR society. Make sure that you get to them first, and win them over immediately.
This isn't the only way to create fans and win over their time and money, but it's just part of a multi-pronged effort to get people to reecognize and experiment with your brand and product. Every successful off-field team has excellent city-wide branding.