The author of the pollination guide on pinguicula.org seems to agree with Zero:
Originally Posted by Zero
"There are several reasons why pollination may not succeed and they are not all well understood....One of your partners may be infertile. This has developed on several Mexican species that have been in cultivation for too long. The origin of this lack of fertility is unknown and may stem from past mass in vitro cultivation with the use of synthetic hormones. In this case, male and female parts may not be un-functional at the same time so that your plant may still be receptive to the pollen of another species or yield viable pollen while being auto-infertile. One classic example is made by P. esseriana and P. ehlersiae which are non auto-fertile in European collections. However, the 2 can be crossed successfully when the cross is carried in one direction only!"
They also recommend using a toothpick because it is invasive to the anthers and less so to the rest of the flower:
"The use of a sharp instrument to collect the pollen is also advisable because it helps in the breakage of the antherís membrane and the release of the pollen grains it contains. Personally, I use a wood toothpick. They can be used as such or flattened and sharpened on one end with a blade to fit the size of the stigma lip. This will allow more pollen to be collected and inflict less damage to the flower structures."
The hobbyist is extremely risk-averse, but doesn't even offer anecdotal evidence to support his claims. I've been pretty rough when pollinating pings this season, and have been rewarded with good seed-sets. As far as virus-infection goes...I guess we'll have to see.