Sampling the Dirac function
I completely agree with Juancho's answer. I would just like to add a few things. I think the main problem is the misunderstanding which becomes evident in the last sentence of the question: "... can the Dirac function be sampled?" The Dirac impulse is NOT an ordinary function having definite values for every $t$, but it is a distribution (even though it is often called 'Dirac function'). One should therefore not try to 'evaluate' (or sample!) it. What is important about the Dirac impulse are its integral properties:

$$\int_{-\infty}^{\infty}\delta(t)dt = 1$$
and
$$\int_{-\infty}^{\infty}\delta(t-t_0)f(t)dt = f(t_0)$$

As Juancho already pointed out, the square of a Dirac impulse $\delta^2(t)$ is not defined. So if you were to sample a Dirac impulse, you would get the undefined result

$$\sum_n\delta(t-nT)\delta(t)=\delta^2(t)$$

Dirac impulses are a convenient tool for analyzing linear time-invariant systems but they should be treated with care because common types of  processing performed on ordinary signals (such as sampling) may lead to undefined and meaningless results when applied to Dirac impulses.