It does take a while to develop a taste for tobacco. You have to taste different leafs and get a set comparison in mind to be able to start pulling out the delicate nuisance of hay, oatmeal, spice, earth, etc... I was smoking about 12-15 pipes a day to start out, so I think that may be why I was more quickly able to start getting these nuisance... that and the help of one of our forum members who leads coffee tastings gave me a few pointers.
To me, there is not a single tobacco that tastes like ashtray. I can't imagine that would remain a popular blend, or even remain on the market for long.
If you have poor memory retention for things like tastes, smells, or even pictures... (how long can you retain all of the details that you see in an image, or retain all of the details that you taste in foods) it may be harder to smoke just once a day and be able to start delving into the details of flavor. If you do only smoke once or twice a day, maybe try smoking two pipes at once with different tobaccos loaded. You can do a more immediate differential between the two.
In the beginning we were all focused on slowing down till we thought we could slow down any more... then we slowed our smoking down even more. The flavor comes when you are smoking it at the very edge of going out. Relights are fine, don't puff to keep it going. Just keep a lighter handy.
One of the hardest things to overcome early on is when you do get a good flavor, DO NOT START PUFFING HARDER. This will kill that flavor you were getting. If anything, slow down more when you start to taste things.
It's hard. If this were easy then any idiot would be able to do it. Keep trying, slow and easy.