I very occasionally watch the team nearest to where I live - Forest Green Rovers.
Currently struggling against relegation in their 13th consecutive season in the Conference. Most of those seasons have been spent fighting relegation, and on two occasions they were actually relegated, but got reprieved because of financial problems at other clubs!
As you have said with Boston, although the football is often not great it is usually an enjoyable day out. And poor results do not bring with them the hysteria that tends to greet some of United's poor results.
I think this is down to expectation. We see ourselves as a club that ought to be in the championship or higher. The fact that we are now virtually certain of third division football is seen as evidence of gross mismanagement. In most supporters eyes our 'natural' place is upper half of the championship/struggling premier league. Most feel that we are now below that level in large part because of a series of very poor decisions made at the top of the club.
At Forest Green there isn't any sort of great expectation. Forest Green is really just a hamlet with a couple of housing estates attached to it on top of a hill about three quarters of a mile outside a very small town called Nailsworth (populaton approx 5,000 - including Forest Green) and I don't think it's disrespectful to say that the club is punching well above it's weight. The fact that the club has now been in the Conference for 13 seasons would be the equivalent of a club like say Dagenham and Redbridge or Yeovil getting into the premier league and staying there for 13 years. Staying in the Conference is the goal and every season that they remain there is seen as a successful season. Relegation would be disappointing, but no disgrace.
However, with United getting established in the premier league is seen as the first aim. And our expectations were raised even higher at the end of the 2005-6 season when we were told that we weren't going to go down and that European football in 5 years was the aim. Well 5 years later the reality is in stark contrast to the stated aim. Raising expectations doesn't help. All it does is feed the hysteria when things aren't going well.
Sometimes I think you're better off being a Forest Green fan. No raised expectations and content with your place in the grand scheme of things!