I use Nanogen and no one has ever picked up on it. I used Toppik when I started out and found that it was easier to spot. When I went on my first holiday with my new girlfriend 3 years ago she goes 'what is that on your forehead?'. It was 6am and I had hurriedly done my hair before meeting her at the airport. I had a very small amount of residue on my forehead! I almost died on the spot. Luckily she knows I use gels (people make jokes at me for my 'nice' styled thick hair with lots of gel if only they knew!!!) so I said 'oh, it's just some residue from this new styling mud thing I've been using lately!'. She bought it. My tips:
1. No to too much Toppik - I tried to overcompensate my lack of time by putting loads on. Big mistake. Do not use too much!
2. Toppik instead of Nanogen is a mistake - Nanogen is MUCH better as particles seem smaller and blend more easily.
3. Spend enough time doing your hair. Unfortunately us baldos need extra time. Do not put more on to save time or if you're in a hurry. Worst case scenario dress casual and wear a baseball cap.
4. Good lighting! Make sure you have a harsh light in your bathroom. Use a wet wipe to take away any stray Nanogen particles.
5. Practice your hair style - I use a messy style, not spiked up. Bit of hair over forehead to cover up anything. I've combed my hair up and it seemed fine, but I feel safer with this.
If you have enough natural hair left and you do it right, you will have a thick head of hair for a few more years! Jump on treatments, don't rely on just this!