Your initial post was that you rejected their appeal because
1) you implied that if you gave to them you couldn't/
wouldn't give to a local shelter,

Actually this was in my second post, not my first post. Hopefully I've
clarified things here.

and 2) their appeal was to
people's empathy.

There is a difference between appeal to empathy, and appeal to guilt (at
least to me there is). Appealing to empathy is about trying to make people
understand a problem, and feel moved to do something about it (and doing
something is therefore something you can feel good about). Appeal to guilt
(in my eyes) is about trying to make people feel like they are bad people
for not doing 'x' (rather than good for doing 'x'). As a rule, I refuse to
give to any organization that tries to make me feel guilty. I feel similarly
about charities that send out 'freebies' (Christmas cards, address labels,
calendars, etc) and then ask you for a donation. Similar arguments against
the 'suggested donations', or 'recurring donations' that many charities have
decided to put on their solicitations (some of which are ridiculously huge).

I get sick and tired of seeing "Yes, I'd like to donate [ ] $50, [ ] $100,
[ ] $150, [ ] other ____" on the back of a charitable solicitation I'd
actually think about contributing to. Frankly if I want to contribute $5,
they should be grateful for it, not try to manipulate me in to donating
more. It must work though, because they continue to do it. It just won't
work on me.

I think the first is not a good general
objection (I give to more than one charity, as do most of my
friends) and the second is just kind of sociopathic. I
think it's good that you changed your arguments.

I've decided that my personal contributions are based on who comes to my
door. If someone cares enough about a charity to physically come around to
my door, then the least I can do is give them a few dollars (assuming its
not a 'cause' I object to).

Dale