In their Consumer Reports style ratings, NumbersUSA ranks Paul as "Bad" on Amnesty. Their position is total opposition to amnesty in any form. Yet that has also been Paul's position for years. He made it clear on the Stossel show and in a 2007 presidential forum he said "I would not sign a bill like [comprehensive immigration reform], because it would be amnesty." That has always been his position. How can that earn him their second worst rating on the issue?
They also give Paul their third worst rating of "Unhelpful" on Border Security, yet Paul voted for the construction of a border fence, the kind of spending he normally opposes on principle. They also rated him "Bad" on Reduce Overall Immigration, yet Paul supported cutting off visas for students from terrorist nations, voted to deport illegals who received hospital treatment, and has a 100% rating from FAIR on reducing immigration.
These low ratings in ares where Paul has a strong anti-immigration record suggest that NumbersUSA may be pursuing some sort of political agenda beyond their stated concerns about immigration. It's like they were looking for ways to specifically hurt Paul with their constituency. This seems grossly unfair and you have to wonder what hidden agenda they are really pursuing. They seem more anti-liberty than they are anti-immigration. Perhaps they started from some faulty assumptions about Paul, but he really isn't a doctrinaire open-borders style libertarian. His positions are much more traditionally consevative.
The other aspect of this is the question of whether a low rating from NumbersUSA is really such a bad thing. Their positions on immigration and related issues are so extreme that they are far outside of the norm for the Republican Party and the political right in general. It's arguable that a low rating from NumbersUSA is a sign that you have some good sense on immigration issues. They may be trying to sink Paul unfairly, but that might end up helping him with the larger section of the population which doesn't believe in draconian anti-immigrant policies.