On Slippery Slopes--Four Problems with the Argument

There are at least four problems with slippery slope arguments in general and with the argument as applied to the issue of "gay marriage" in particular. Here are the four which I have in mind:

1. The argument fails on account of being unable to prove that A will lead to B, C, and D.
2. The argument fails because A is worth the risk of B,C, and D.
3. B, C, and D are not so bad as A itself.
4. B, C, and D are actually desired ends of A.

Note that here "A" is the stand in for gay marriage," and B,C, and D are stand-ins for additionally consequences which might follow from it (not necessarily three in number). These 4 problems are essentially the counter-arguments deployed against the slippery slope argument. It should also be noted that there can be more than one set of B, C, and D. For example, "gay marriage" can be said by one slippery slope to lead to legal recognition of polygamy, incest, pedophilia, bestiality, etc. until marriage is utterly meaningless; it can also be said to lead to the loss of tax-exempt status of religious organizations, restrictive speech codes, requirements that conscientious objectors participate in events celebrating "gay marriage" (whether pride parades or the actual "wedding" ceremonies, receptions, etc.), to loss of religious freedoms in general and ultimately a persecution of certain religions (namely, faithful Christians).